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+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**Q.1101**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# **INTERWORKING WITH SATELLITE MOBILE SYSTEMS**
+
+## --- **GENERAL REQUIREMENTS FOR THE INTERWORKING OF THE TERRESTRIAL TELEPHONE NETWORK AND INMARSAT STANDARD A SYSTEM**
+
+**ITU-T Recommendation Q.1101**
+
+(Extract from the *Blue Book*)
+
+---
+
+## NOTES
+
+1 ITU-T Recommendation Q.1101 was published in Fascicle VI.14 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## GENERAL REQUIREMENTS FOR THE INTERWORKING OF THE TERRESTRIAL TELEPHONE NETWORK AND INMARSAT STANDARD A SYSTEM
+
+## 1 Introduction
+
+1.1 The purpose of this Recommendation is to define the general interworking requirements between the telephone network and the INMARSAT Standard A system.
+
+1.2 In order to support automatic working between subscribers in the public telephone service and telephone subscribers to the maritime mobile-satellite service, it is necessary that the interface between the terrestrial telephone network and the maritime satellite system be defined.
+
+1.3 It should be possible to interface the maritime-mobile satellite system with any signalling system standardized by the CCITT for automatic working. In order to facilitate the preparation of the interworking equipment, and also aiming at the international standardization of the service, this Recommendation lists several basic interworking requirements common to all signalling systems.
+
+1.4 More specific interworking requirements applicable to System No. 5 are given in Recommendation Q.1103 and System R2 are given in Recommendation Q.1102.
+
+1.5 A brief description of the INMARSAT Standard A system is given in Annex A. SDL descriptions of incoming and outgoing signalling procedures for the INMARSAT system are given in Annexes B and C respectively.
+
+1.6 Interworking between the telephone network/ISDN and other INMARSAT systems is given in separate Q-Series Recommendations.
+
+## 2 Maritime satellite switching centre
+
+For the purpose of this Recommendation the term Maritime Satellite Switching Centre (MSSC) is used to indicate the interworking point between the terrestrial telephone network and the maritime satellite system. The maritime satellite switching centre (MSSC) may be located at the antenna site of the coast earth station [1] and operate as an independent international switching centre connected to one or more international switching centres (ISCs) or national switching centres, or it may be remote as a supplement to or as a part of an international switching centre.
+
+## 3 List of general Series Q Recommendations
+
+Due regard should be paid to the following general Series Q Recommendations:
+
+- Q.11, Q.11*bis*, Q.11*ter*, and Q.12, Q.13, numbering and routing plan
+- Q.14, means of controlling the number of satellite links
+- Q.15 through Q.22, general Recommendations
+- Q.23, technical features of push-button telephone sets
+- Q.25, splitting arrangement
+- Q.26 through Q.33, miscellaneous provisions
+- Q.35, tones of national signalling systems
+- Q.40 through Q.45, transmission characteristics
+- Q.102, facilities provided in international automatic working
+- Q.103, numbering used
+- Q.104, language digit or discriminating digit
+
+- Q.105, national (significant) number
+- Q.106, the sending-finished signal
+- Q.107, sending sequence of forward-address information
+- Q.107*bis*, analysis of forward-address information for routing
+- Q.109, transmission of the answer signal
+- Q.112 through Q.114, transmission clauses
+- Q.115, control of echo suppressors
+- Q.116 through Q.118*bis*, abnormal conditions.
+
+## 4 Sending sequence of numerical (or address) signals
+
+### 4.1 *Calls toward ship earth station [2] (shore-to-ship)*
+
+In most cases the MSSC will not need the information contained in the S-digit of the country code 87S. In this situation the sequence of forward-address information sent to the MSSC should be as for a terminal international call.
+
+Cases may arise where an MSSC requires the S-digit to distinguish between ocean areas, satellite systems or VHF/UHF vs. satellite. In this situation the sequence of forward-address information should be as for an international transit call, i.e. the sequence includes the country code 87S.
+
+### 4.2 *S-digit*
+
+It is a matter for the terrestrial subscriber to choose the proper S-digit and the MSSC to be used will be decided by the outgoing country. (For technical reasons accounting between Administrations should be performed on the basis of only 87S.)
+
+### 4.3 *Calls from ship earth station (ship-to-shore)*
+
+The desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a prefix followed by the full international telephone number required, whether or not the MSSC is located in the required subscriber's country (see also Recommendation Q.11*quater*).
+
+The prefix must be suppressed by the MSSC since it is only required for internal routing in the MSSC.
+
+For calls to subscribers in the MSSC country, the country code should also be suppressed by the MSSC.
+
+A discriminating digit must be inserted by the MSSC according to Recommendation Q.104.
+
+### 4.4 *Operator services*
+
+The desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a two digit prefix, possibly followed by a 1, 2 or 3 digit country code, to identify the type of operator required (see Recommendation Q.11*quater*).
+
+The MSSC could then convert the received dialling information as required for setting up the terrestrial connection to the operator.
+
+### 4.5 *Special service terminations*
+
+The desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a two digit prefix possibly followed by other digits to identify the type of special service termination required. (See Recommendation Q.11*quater*.) The MSSC should convert the received dialling information as required for setting up the terrestrial connection.
+
+## 5 Special requirements related to setting-up and clearing of automatic calls
+
+### 5.1 *Setting-up time for shore originated calls*
+
+The setting-up time for shore originated calls should be as short as possible. If the MSSC has not been able to establish the connection within a period of 20 seconds after receipt of all address digits, a congestion indication should be returned.
+
+*Note* - In maritime satellite systems the setting-up time is not controlled by each individual MSSC but may depend on the overall traffic load in the system and on the assignment procedure used. For several reasons the setting-up time of the radio path is likely to be longer than the setting-up time of the subscriber connection in terrestrial systems.
+
+### 5.2 *Transmission of answer signal*
+
+5.2.1 When the maritime satellite switching centre (MSSC) detects the answer signal from the maritime satellite system, the MSSC must remove the ringing tone, through-connect the circuit and return the answer signal as soon as possible to the terrestrial switching centre.
+
+Precautions should be taken at the MSSC to avoid interpreting an interruption of the satellite link as an answer signal.
+
+5.2.2 For ship originated calls the maritime satellite system should preferably include provisions for transferring the answer signal to the ship earth station.
+
+### 5.3 *Seizure of a terrestrial circuit from the MSSC*
+
+The maritime satellite switching centre should not seize a terrestrial circuit before each of the following conditions has been met:
+
+- the satellite channel has been assigned;
+- the continuity of the satellite channel has been verified;
+- all digits necessary for routing decision by the maritime satellite switching centre have been received.
+
+### 5.4 *Clear-back conditions*
+
+5.4.1 The clear-back/re-answer sequence may not apply for shore originated calls, in which case the satellite link will be released when a clear-back signal is detected at the maritime satellite switching centre from the satellite link, without waiting for a clear-forward signal from the terrestrial network.
+
+Precautions should be taken either at the MSSC or at the ship earth station in order to avoid unintentional clearing.
+
+5.4.2 For ship originated calls the normal clear-back procedures should apply (see Recommendation Q.118).
+
+### 5.5 *Clear-forward*
+
+When detecting a clear-forward from the satellite link, the MSSC should immediately pass the clear-forward signal into the terrestrial network.
+
+When detecting a clear-forward from the terrestrial network, the release guard (and clearing) sequence should follow the procedures defined for the signalling system used.
+
+### 5.6 *Splitting arrangement*
+
+When in-band signalling is used over the satellite link for setting-up and clearing of the link, a splitting arrangement shall be provided in order to avoid that signalling tones are passed into the terrestrial network. The splitting time shall be less than 20 ms.
+
+In order to protect the maritime satellite system from line signals used on terrestrial signalling systems, it should be observed that such signalling tones passing through splitting arrangements in the terrestrial network may have a maximum duration of 50 ms.
+
+## 6 Audible tones sent by the MSSC
+
+Tones sent by the maritime switching centre (MSSC) should have the following characteristics:
+
+|                           |                                                                                    |
+|---------------------------|------------------------------------------------------------------------------------|
+| Dial tone:                | 425 Hz (1.5 seconds maximum, minimum is determined by receipt of first dial digit) |
+| Ringing tone:             | 425 Hz (1 second on, 4 seconds off, immediate ringing)                             |
+| Busy tone:                | 425 Hz (1/2 second on, 1/2 second off)                                             |
+| Congestion tone:          | 425 Hz (1/4 second on, 1/4 second off)                                             |
+| Special information tone: | as defined in Recommendation Q.35.                                                 |
+
+*Note* - The dial tone is given as 1.5 seconds pulse in order to avoid subscribers' confusion due to the two-way transmission delay of 0.5 seconds. If the normal continuous tone with interruption after the receipt of the first digit was used, the delay would cause the tone to stay on after entry of the first digit.
+
+## 7 Control of echo suppressors
+
+Since all calls to and from a ship earth station will include a satellite link, appropriate actions must be taken to insert an incoming or outgoing half-echo suppressor at the MSSC or at an international exchange closer to the terrestrial subscriber. The ship earth station will connect to the satellite link on a 4-wire basis or will be provided with the equivalent of a half-echo suppressor. In order to reduce the analysis and control requirements at the MSSC it may prove convenient to carry out all echo suppressor control at one of the international exchanges rather than at the MSSC. This is most easily achieved by fitting permanent half-echo suppressors at the ISC end of each MSSC-ISC circuit. In any case the overall echo control requirements are the same as specified in Recommendation Q.115.
+
+### 7.1 *Terrestrial signalling systems with signals for control of echo suppressors*
+
+#### 7.1.1 *Ship original calls*
+
+The MSSC should send an echo suppressor indicator informing transit centres or incoming centres whether or not an incoming half-echo suppressor should be included.
+
+Insertion of an incoming half-echo suppressor will always be requested if the MSSC does not carry out echo suppressor control.
+
+#### 7.1.2 *Shore originated calls*
+
+The MSSC will decide whether or not to insert an outgoing half-echo suppressor depending on the received echo suppressor indicator. If echo control is not performed at the MSSC, the echo suppressor indicator will always inform the MSSC that an outgoing half-echo suppressor has already been included.
+
+### 7.2 *Terrestrial signalling systems without signals from control of echo suppressors*
+
+When signals for the control of echo suppressors are not available on the particular terrestrial route, significant advantage is to be gained by carrying out the echo suppressor control at the international exchange. In any case the following rules should be observed:
+
+#### 7.2.1 *Ship originated calls*
+
+- When the terrestrial connection between the outgoing ISC, (or MSSC) and the incoming ISC (or national incoming switching centre) does not normally require the use of echo suppressors, the outgoing ISC (or MSSC) should enable (or insert) an incoming half-echo suppressor associated with the satellite link.
+- When the terrestrial connection between the outgoing ISC (or MSSC) and the incoming ISC (or national incoming switching centre) normally requires the use of echo suppressors, the outgoing ISC (or MSSC) should disable (or should not insert) any half-echo suppressors associated with either the satellite link or the terrestrial link.
+
+#### 7.2.2 Shore originated calls
+
+- When the international connection between the outgoing ISC and the incoming ISC (or MSSC) does not normally require the use of echo suppressors, the incoming ISC (or MSSC) should enable (or insert) an outgoing half-echo suppressor associated with the satellite link.
+- When the international connection between the outgoing ISC and the incoming ISC (or MSSC) normally requires the use of echo suppressors, the incoming ISC (or MSSC) should disable (or should not insert) any half-echo suppressors associated with either the satellite or terrestrial link.
+
+## 8 Handling of group calls
+
+### 8.1 General
+
+A group call is a simultaneous call to a given group of ships. Such calls are identified by the following international number:
+
+$$87S0X_2X_3 \dots X_k$$
+
+where the first digit of the ship station number has the fixed value 0. The remaining digits determine which group of ships is being addressed.
+
+Facilities for originating group calls from operators either in the MSSC country or another country may be readily made available by permitting such calls only when the Z digit is a language digit. Group calls originating from ordinary telephone subscribers should not be permitted so long as calling line identification is not available.
+
+### 8.2 Barring at the ISC of origin
+
+In order to avoid setting up of the international chain for unauthorized group calls from ordinary subscribers, barring of such calls should, as a general rule, be done at the ISC of origin.
+
+### 8.3 Barring at the MSSC
+
+Barring should also be provided at the MSSC in order to reject group call attempts from ships or from subscribers in countries where barring at the outgoing ISC is not possible.
+
+## 9 Avoiding two or more satellite links in tandem
+
+### 9.1 Shore originated calls
+
+The country code 87S should be analysed at all transit centres where the call may either be routed on a circuit containing a satellite link or on a circuit not containing a satellite link. The latter circuit should always be chosen (see Recommendation Q.14).
+
+### 9.2 Ship originated calls
+
+If the signalling system provided between the MSSC and the terrestrial network contains signals which may be used to indicate that one satellite link is included, such signals should be used.
+
+If the signalling system does not contain such signals, the outgoing ISC should avoid forwarding the call on an outgoing circuit which includes a satellite link. If, however, the signalling system employed between the outgoing ISC and the next ISC in the connection contains such signals, the outgoing ISC should insert the required information. The outgoing ISC could base its procedure upon incoming route identification.
+
+## 10 Operator assistance for semi-automatic shore originated calls
+
+If code 11/12 assistance facilities are not provided at the MSSC, then arrangements should be made to intercept such calls at the preceding ISC and route them to an appropriate operator.
+
+It may be advantageous for Administrations to provide a publicized number (e.g. C12XXXX) for specialized assistance on calls to the maritime network.
+
+## ANNEX A
+
+(to Recommendation Q.1101)
+
+### **Brief description of the INMARSAT Standard A system**
+
+### A.1 *Introduction*
+
+This annex describes the signalling in the INMARSAT Standard A system in a multiple Maritime Satellite Switching Centre (MSSC) configuration, i.e., there is more than one MSSC serving an ocean region. Automatic call set-up and clearing are illustrated below. For calls which cannot be completed, the subscriber will receive from the MSSC or the terrestrial network the proper audible tone which describes the call status (i.e., busy tone, congestion tone).
+
+### A.2 *System configuration*
+
+The INMARSAT system is composed as shown in Figure A-1/Q.1101. Only the components required for interfacing the telephone network are shown. There are additional interfaces similar to the MSSC for interfacing the telex network and the international public data network.
+
+The purpose of the MSSC is defined in § 2 of the Recommendation.
+
+There is one operating Network Coordination Station (NCS) in each ocean area (there may in addition be one or more standby NCSs per ocean area). The main functions of the NCS are as follows.
+
+The ship earth stations can only monitor one calling channel in the shore-to-ship direction. This calling channel, denoted as the common assignment channel, is transmitted by the NCS. Each coast earth station transmits its own calling channel which is monitored by the NCS for relaying signalling messages from a coast earth station to a ship.
+
+The NCS also performs all assignment of telephone channels on a call-by-call basis and monitors the actual use of the channels for maintenance purposes. The NCS keeps an up-dated list of all busy ships in the ocean area. If a coast earth station calls a busy ship, the NCS may thus return a ship busy indication to the calling coast earth station on the common assignment channel.
+
+The procedures are further described below.
+
+### A.3 *Ship earth station originated calls*
+
+The normal call set-up procedure for automatic call processing from a ship earth station is shown in Figure A-2/Q.1101. The ship earth station transmits an out-of-band request message which includes the type of call desired, the identify of the MSSC through which the terminal wishes to communicate and the identification number of the ship earth station.
+
+![Diagram of the maritime satellite system composition for interconnection with the telephone network. A ship earth station on a vessel is connected via a dashed line to a coast earth station. This coast earth station is connected to an MSSC (Mobile Switching Center), which is in turn connected to a telephone network. Another coast earth station is shown connected to an NCS (Network Coordination Station), which is connected to an MSSC. A dashed line with an asterisk (*) connects the NCS to the MSSC. The diagram is labeled 'CCITT - 59 700'.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+Diagram of the maritime satellite system composition for interconnection with the telephone network. A ship earth station on a vessel is connected via a dashed line to a coast earth station. This coast earth station is connected to an MSSC (Mobile Switching Center), which is in turn connected to a telephone network. Another coast earth station is shown connected to an NCS (Network Coordination Station), which is connected to an MSSC. A dashed line with an asterisk (\*) connects the NCS to the MSSC. The diagram is labeled 'CCITT - 59 700'.
+
+\* The NCS of an ocean area will normally be co-located with an MSSC of that area.
+
+FIGURE A-1/Q.1101
+
+#### **Composition of the maritime satellite system for interconnection with the telephone network**
+
+The MSSC upon reacting to the received *request* message, sends a *Request for Assignment* message to the Network Coordination Station (NCS). The NCS receiving the *request for assignment* message assigns a channel (frequency) and transmits this information in an *assignment* message to both the MSSC and the ship earth station. Both the MSSC and ship earth station receive the *assignment* message, automatically select the correct frequency, and initiate a continuity by transmitting a 2600 Hz tone.
+
+When continuity has been established, the MSSC sends a dial tone pulse to the ship earth station. The ship earth station subscriber then dials in the desired prefix, country code and national significant number followed by an end-of-selection signal. The signals are transferred as in band push button signals on the satellite link.
+
+The MSSC proceeds to select a terrestrial trunk and follows the standard signalling sequences of the signalling system used towards the ISC (Figure A-2/Q.1101). The ringing tone from the terrestrial network is allowed to pass directly to the ship earth station subscriber. When the terrestrial party answers the call, the ISC passes the answer signal to the MSSC and the international connection is established. The answer signal, if implemented, may then be passed to the ship earth station<sup>1)</sup>.
+
+### **A.4 Terrestrial originated calls**
+
+The normal call set-up procedure for automatic call processing from the terrestrial network to a ship earth station is shown in Figure A-3/Q.1101. The ISC selects a circuit and sends the seizing signal and the mobile terminal identification digits to the MSSC in accordance with the procedures used in the terrestrial signalling system. The MSSC then sends a *request-for-assignment* message to the NCS containing the ship earth station identity. The NCS responds by sending an *assignment* message to both the MSSC and the ship earth station. The MSSC and the ship earth station activate their carriers and send a 2600 Hz tone. Upon receipt of the 2600 Hz tone from the ship earth station the MSSC interprets this as an address complete condition, sends the ringing tone to the terrestrial network and stops sending 2600 Hz to the ship earth station. When the operator or subscriber at the ship earth station answers, the ship earth station discontinues sending its 2600 Hz tone.
+
+The MSSC recognizes the cutting of the 2600 Hz tone as an answer signal from the ship earth station and begins the answer sequence toward the ISC as shown in Figure A-3/Q.1101.
+
+<sup>1)</sup> This is currently under study by INMARSAT.
+
+![Sequence diagram for ship earth station originated calls (Figure A-2/Q.1101).](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+This sequence diagram illustrates the call setup process for a ship earth station originated call. The participants are the Ship earth station, Network coordination station (NCS), Addressed maritime satellite switching centre, and ISC. The process begins with a 'Request' from the ship to the NCS, followed by a 'Request for assignment' from the NCS to the switching centre. An 'Assignment' message is returned from the switching centre via the NCS to the ship. A 'continuity check' is performed between the ship and the switching centre, involving 'SF tone on', 'Carrier on', and 'SF tone off' signals. A '1,5 s Proceed-to-select tone' is sent from the switching centre to the ship. 'Subscriber keying' is indicated at the ship. 'Digits (human cadence)' are sent from the ship to the switching centre. The switching centre sends a 'Seizing' signal to the ISC, followed by 'Inter register signalling'. A 'Ringing tone' and 'Answer' are exchanged between the switching centre and the ISC. Finally, a 'Cut through' is established between the ship and the ISC, and the call is in progress. The diagram is labeled CCITT-39262.
+
+Sequence diagram for ship earth station originated calls (Figure A-2/Q.1101).
+
+Note - If implemented.
+
+FIGURE A-2/Q.1101
+
+#### Ship earth station originated calls
+
+![Sequence diagram for terrestrial originated automatic call (Figure A-3/Q.1101).](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg)
+
+This sequence diagram illustrates the call setup process for a terrestrial originated automatic call. The participants are the Ship earth station, Network coordination station (NCS), Addressed maritime satellite switching centre, and ISC. The process begins with 'Ringing Off-hook' at the ship. A 'Request for assignment' is sent from the switching centre to the NCS. An 'Assignment' message is returned from the NCS to the ship. A 'continuity check' is performed between the ship and the switching centre, involving 'SF tone on', 'Carrier on', and 'SF tone off' signals. The switching centre sends a 'Seizing' signal to the ISC, followed by 'Inter-register signals' and 'Satellite trunk access'. An 'Address complete' message is sent from the switching centre to the ISC, followed by a 'Ringing tone'. An 'Answer' is received from the ISC by the switching centre. Finally, the call is in progress. The diagram is labeled CCITT-39271.
+
+Sequence diagram for terrestrial originated automatic call (Figure A-3/Q.1101).
+
+FIGURE A-3/Q.1101
+
+#### Terrestrial originated automatic call
+
+### A.5 Automatic clearing of calls
+
+Whether a telephone call originated from a ship earth station or from the terrestrial network, the MSSC, upon receiving a clear-forward signal, will begin to clear the call independently in each direction.
+
+The MSSC, receiving a 2600 Hz clearing tone from a ship earth station will initiate clearing toward the terrestrial network in accordance with procedures defined for the signalling system used between the MSSC and the ISC. This applies to both clear-forward and clear-back from the ship earth station. Clearing will also be continued in the maritime satellite system independent of the terrestrial network.
+
+Clearing initiated in the terrestrial network would be recognized by the MSSC receiving the appropriate clear-back or clear-forward signal. For clear-forward, the MSSC would continue clearing with normal terrestrial procedures and begin clearing the maritime satellite circuit. For clear-back from the terrestrial network, normal time-out supervision will take place and clear-forward will commence either after expiry of time-out or after receipt of a clear-forward from the ship, whichever happens first.
+
+As examples of clearing sequences, Figure A-4/Q.1101 illustrates the clearing of a ship earth station originated call and Figure A-5/Q.1101 illustrates the clearing of a call originated in the terrestrial network. For a terrestrial originated call which has clearing initiated by the ship earth station, the satellite circuit is cleared after the MSSC recognizes the stopping of the ship earth station carrier. The terrestrial circuit is held until the end of release guard sequence as shown in Figure A-5/Q.1101.
+
+![Sequence diagrams for clearing ship earth station originated calls. Diagram (a) shows clearing initiated by the terrestrial network (Clear-back) with a time-out at the MSSC. Diagram (b) shows clearing initiated by the ship earth station (SES) going on-hook. Both diagrams show the flow of signals (SF tone, carrier off, Clear forward, Release guard) between the Ship earth station, Network coordination station (NCS), Addressed MSSC, and ISC. Diagram (b) includes a 'Subscriber on-hook' event at the ship station and a 'Notification of ship clearing' signal to the MSSC.](7e670a2b556b53ea9002dfff3a420e08_img.jpg)
+
+```
+
+sequenceDiagram
+    participant SES as Ship earth station
+    participant NCS as Network coordination station (NCS)
+    participant MSSC as Addressed MSSC
+    participant ISC as ISC
+
+    Note over SES, ISC: a) Clear-back from terrestrial network; clearing by MSSC on time-out
+    ISC->>MSSC: Clearback
+    Note right of MSSC: Time out as defined in Recommendation Q.118
+    MSSC->>SES: SF tone on
+    MSSC->>ISC: Clear forward
+    SES-->MSSC: SES*) carrier off
+    ISC->>MSSC: Release guard
+    SES->>NCS: SF tone and MSSC carrier off
+    NCS->>MSSC: Notification of ship clearing
+
+    Note over SES, ISC: b) Clearing by ship earth station
+    Note left of SES: Subscriber on-hook
+    SES->>MSSC: SF tone on
+    Note left of SES: ≈ 2 s
+    MSSC->>ISC: Clear forward
+    MSSC-->SES: MSSC carrier off
+    ISC->>MSSC: Release guard
+    SES->>NCS: SF tone and SES carrier off
+    NCS->>MSSC: Notification of ship clearing
+    Note right of MSSC: t < 4 s
+
+```
+
+a) Clear-back from terrestrial network; clearing by MSSC on time-out
+
+b) Clearing by ship earth station
+
+CCITT-39281
+
+Sequence diagrams for clearing ship earth station originated calls. Diagram (a) shows clearing initiated by the terrestrial network (Clear-back) with a time-out at the MSSC. Diagram (b) shows clearing initiated by the ship earth station (SES) going on-hook. Both diagrams show the flow of signals (SF tone, carrier off, Clear forward, Release guard) between the Ship earth station, Network coordination station (NCS), Addressed MSSC, and ISC. Diagram (b) includes a 'Subscriber on-hook' event at the ship station and a 'Notification of ship clearing' signal to the MSSC.
+
+SES = Ship earth station
+
+FIGURE A-4/Q.1101
+
+#### Clearing sequences for ship earth station originated calls
+
+![Two sequence diagrams showing call clearing procedures. Diagram (a) shows 'Clearing by terrestrial network' involving Ship earth station, Network coordination station (NCS), Addressed MSSC, and ISC. Diagram (b) shows 'Clearing by ship earth station' involving Subscriber on-hook, Ship earth station, NCS, Addressed MSSC, and ISC. Both diagrams show signal flows like 'SF tone on', 'SES carrier off', 'MSSC carrier off', 'Notification of ship clearing', 'Clear forward', 'Release guard', 'Clearback', and 'Terrestrial circuit held'.](d4af765160d04ecef538e5066006dc77_img.jpg)
+
+*a) Clearing by terrestrial network*
+
+*b) Clearing by ship earth station*
+
+CCITT-39291
+
+Two sequence diagrams showing call clearing procedures. Diagram (a) shows 'Clearing by terrestrial network' involving Ship earth station, Network coordination station (NCS), Addressed MSSC, and ISC. Diagram (b) shows 'Clearing by ship earth station' involving Subscriber on-hook, Ship earth station, NCS, Addressed MSSC, and ISC. Both diagrams show signal flows like 'SF tone on', 'SES carrier off', 'MSSC carrier off', 'Notification of ship clearing', 'Clear forward', 'Release guard', 'Clearback', and 'Terrestrial circuit held'.
+
+FIGURE A-5/Q.1101
+
+#### **Clearing sequences for terrestrial originated calls**
+
+## ANNEX B
+
+(to Recommendation Q. 1101)
+
+### **Logic procedures for incoming INMARSAT Standard A signalling system (ship originated call)**
+
+This annex only includes those elements of the Standard A INMARSAT system which have to be implemented for interworking purposes.
+
+Internal procedures such as those required for setting-up and clearing of the satellite link are not shown. They are only indicated by task symbols.
+
+Other procedures not shown are:
+
+- interruption control procedures related to the satellite link;
+- pre-emption procedures for assigning channels to distress call.
+
+For more details on the first generation INMARSAT Standard A signalling system, see Annex A.
+
+![State transition diagram for incoming INMARSAT Standard A signalling system. States are numbered 00 to 07. Transitions: 00 to 01, 01 to 02, 02 to 03, 03 to 04, 04 to 05, 05 to 07, 07 to 00, 07 to 02, 07 to 03, 07 to 04, 07 to 06, 06 to 02, 06 to 03, 06 to 04. A label 'CCITT - 59710' is present below the diagram.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+State transition diagram for incoming INMARSAT Standard A signalling system. States are numbered 00 to 07. Transitions: 00 to 01, 01 to 02, 02 to 03, 03 to 04, 04 to 05, 05 to 07, 07 to 00, 07 to 02, 07 to 03, 07 to 04, 07 to 06, 06 to 02, 06 to 03, 06 to 04. A label 'CCITT - 59710' is present below the diagram.
+
+CCITT - 59710
+
+| State number | State description                 | Sheet reference | Timers running |
+|--------------|-----------------------------------|-----------------|----------------|
+| 00           | Idle                              | 1               |                |
+| 01           | Wait for continuity               | 1               |                |
+| 02           | Wait for digits                   | 1               | t <sub>1</sub> |
+| 03           | Wait for result of digit analysis | 2               | t <sub>1</sub> |
+| 04           | Wait for call set-up              | 2               | t <sub>1</sub> |
+| 05           | Connected                         | 2               |                |
+| 06           | Wait for clear-forward            | 2               | t <sub>2</sub> |
+| 07           | Wait for clearing                 | 1               |                |
+
+FIGURE B-1/Q.1101
+
+#### **State overview diagrams for incoming INMARSAT Standard A signalling system**
+
+*Supervisory timers for incoming INMARSAT Standard A signalling system*
+
+t<sub>1</sub> = 15-20 seconds
+
+t<sub>2</sub> = 20-30 seconds
+
+FIGURE B-2/Q.1101
+
+#### **Notes to incoming INMARSAT Standard A signalling system**
+
+![Flowchart of Incoming INMARSAT Standard A signalling system. The process starts at IDLE (00), receives a REQUEST FROM SHIP, STORES the MESSAGE, and SETS UP the SATELLITE CHANNEL (with INMARSAT system supervision). It then enters WAIT FOR CONTINUITY (01). If CONTINUITY ESTABLISHED, it sends SPITE 6 CONNECT DIAL TONE, then SPITE 1, and STARTS t1 (15-20 seconds). If UNSUCCESSFUL CALL, it DISCONNECTS the SATELLITE CHANNEL (with INMARSAT system disconnection procedure) and returns to IDLE (00). After START t1, it enters WAIT FOR DIGITS (02). From here, ADDRESS SIGNAL, CLEAR FORWARD, or t1-bar can occur. ADDRESS SIGNAL leads to END OF PULSING. If YES, it goes to SPITE 35, STOP t1, STORE END-OF-PULSING DIGIT, then SPITE 12 (Note 1), and connector 2. If NO, it checks SPITE 11. If YES, it goes to START t1 and connector 1. If NO, it goes to START t1 and connector 1. CLEAR FORWARD leads to STOP t1, SPITE 3, and connector 4. t1-bar leads to SPITE 6 and connector 7. After SPITE 12 or SPITE 3, it enters CLEAR SATELLITE CHANNEL (with INMARSAT system clearing procedure), then WAIT FOR CLEARING (07), CHANNEL RELEASED, and finally IDLE (00).](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+```
+
+graph TD
+    00_1([00 IDLE]) --> RFS[REQUEST FROM SHIP]
+    RFS --> SM[STORE MESSAGE]
+    SM --> SC[SET-UP SATELLITE CHANNEL]
+    SC -.-> S[Signalling procedure defined within the INMARSAT system including time-out supervision]
+    SC --> 01_1([01 WAIT FOR CONTINUITY])
+    01_1 --> CE[CONTINUITY ESTABLISHED]
+    01_1 --> UC[UNSUCCESSFUL CALL]
+    CE --> SDT[SPITE 6 CONNECT DIAL TONE]
+    SDT --> S1[SPITE 1]
+    S1 --> ST1[START t1]
+    ST1 -.-> ST1_T[15-20 seconds]
+    ST1 --> 02_1([02 WAIT FOR DIGITS])
+    UC --> DC[DISCONNECT SATELLITE CHANNEL]
+    DC -.-> D[Disconnection procedure defined within the INMARSAT system]
+    DC --> 00_2([00 IDLE])
+    02_1 --> AS[ADDRESS SIGNAL]
+    02_1 --> CF[CLEAR FORWARD]
+    02_1 --> TB[ $\bar{t}_1$ ]
+    AS --> EP{END OF PULSING}
+    EP -- YES --> S35[SPITE 35]
+    S35 --> ST1_2[STOP t1]
+    ST1_2 --> SED[STORE END-OF-PULSING DIGIT]
+    SED --> S12[SPITE 12 Note 1]
+    S12 --> 2_2((2 2))
+    EP -- NO --> S11{SPITE 11}
+    S11 -- YES --> ST1_3[START t1]
+    ST1_3 --> 1_1((1 1))
+    S11 -- NO --> ST1_4[START t1]
+    ST1_4 --> 1_1
+    CF --> ST1_5[STOP t1]
+    ST1_5 --> S3[SPITE 3]
+    S3 --> 4_2((4 2))
+    TB --> S6[SPITE 6]
+    S6 --> 7_2((7 2))
+    S3 --> 6_2((6 2))
+    6_2 --> CSC[CLEAR SATELLITE CHANNEL]
+    CSC -.-> C[Clearing procedure defined within INMARSAT system including time-out supervision]
+    CSC --> 07_1([07 WAIT FOR CLEARING])
+    07_1 --> CR[CHANNEL RELEASED]
+    CR --> 00_3([00 IDLE])
+    1_1 --> 1_2((1 2))
+    2_2 --> 1_2
+    4_2 --> 1_2
+    7_2 --> 1_2
+    6_2 --> 1_2
+  
+```
+
+Flowchart of Incoming INMARSAT Standard A signalling system. The process starts at IDLE (00), receives a REQUEST FROM SHIP, STORES the MESSAGE, and SETS UP the SATELLITE CHANNEL (with INMARSAT system supervision). It then enters WAIT FOR CONTINUITY (01). If CONTINUITY ESTABLISHED, it sends SPITE 6 CONNECT DIAL TONE, then SPITE 1, and STARTS t1 (15-20 seconds). If UNSUCCESSFUL CALL, it DISCONNECTS the SATELLITE CHANNEL (with INMARSAT system disconnection procedure) and returns to IDLE (00). After START t1, it enters WAIT FOR DIGITS (02). From here, ADDRESS SIGNAL, CLEAR FORWARD, or t1-bar can occur. ADDRESS SIGNAL leads to END OF PULSING. If YES, it goes to SPITE 35, STOP t1, STORE END-OF-PULSING DIGIT, then SPITE 12 (Note 1), and connector 2. If NO, it checks SPITE 11. If YES, it goes to START t1 and connector 1. If NO, it goes to START t1 and connector 1. CLEAR FORWARD leads to STOP t1, SPITE 3, and connector 4. t1-bar leads to SPITE 6 and connector 7. After SPITE 12 or SPITE 3, it enters CLEAR SATELLITE CHANNEL (with INMARSAT system clearing procedure), then WAIT FOR CLEARING (07), CHANNEL RELEASED, and finally IDLE (00).
+
+Note 1 - Includes also translation of prefixes to the appropriate destination number.
+
+FIGURE B-3/Q.1101  
+(sheet 1 of 2)
+
+#### Incoming INMARSAT Standard A signalling system
+
+![Flowchart of the Incoming INMARSAT Standard A signalling system (sheet 2 of 2).](bd0b93e7a46ede276d0a3b79ac487bd9_img.jpg)
+
+The flowchart illustrates the signalling logic for an incoming INMARSAT Standard A call. It begins at connector 2, leading to state 03 (WAIT FOR RESULT OF DIGIT ANALYSIS). From here, multiple signal inputs are monitored: ADDRESS SIGNAL, SPITE 15, 16, 17, 18, 19, SPITE 13, SPITE 14 (Note 2), CLEAR-FORWARD, and  $t_1$ .
+
+- The **ADDRESS SIGNAL** path leads to a decision 'END OF PULSING'. If 'NO', it triggers 'START  $t_1$ '. If 'YES', it proceeds to 'STOP  $t_1$ ', 'STORE END-OF-PULSING DIGIT', and 'SPITE 35', returning to connector 2.
+- The **SPITE 15, 16, 17, 18, 19** path leads to 'YES' or 'NO' for 'EoP RECEIVED'. If 'YES', it triggers 'STOP  $t_1$ ', 'SPITE 6', and 'SPITE 3', then 'START  $t_2$ ' (where  $t_2 = 20-30$  seconds), leading to state 06 (WAIT FOR CLEAR-FORWARD). From state 06, 'CLEAR-FORWARD' leads to 'STOP  $t_2$ ' and connector 4. If 'EoP RECEIVED' is 'NO', it returns to connector 1.
+- The **SPITE 13** path returns to connector 1.
+- The **SPITE 14 (Note 2)** path leads to 'ACTIVATE INTER-WORKING PROCEDURE' and 'WHICH CATEGORY'. Categories include 'Ordinary call' (FITE 17), 'Priority call' (FITE 18), and 'Data call' (FITE 19), all leading to 'FITE 1'. 'FITE 1' leads to 'ANY MORE DIGITS'. If 'YES', it triggers 'START  $t_1$ '. If 'NO', it leads to state 04 (WAIT FOR CALL SET-UP).
+- The **CLEAR-FORWARD** path leads to 'STOP  $t_1$ ' and connector 4.
+- The  **$t_1$**  path leads to 'SPITE 6' and connector 7.
+
+From state 04 (WAIT FOR CALL SET-UP), signals like ADDRESS SIGNAL, BITE 28, CLEAR-FORWARD, BITE 27, and  $t_1$  are monitored:
+
+- ADDRESS SIGNAL** leads to 'FITE 1' and then a decision 'END OF PULSING'. If 'YES', it returns to state 04. If 'NO', it triggers 'START  $t_1$ '.
+- BITE 28** leads to connector 7.
+- CLEAR-FORWARD** leads to 'FITE 22' and connector 4.
+- BITE 27** leads to 'STOP  $t_1$ ' and connector 5.
+- $t_1$**  leads to 'FITE 22', 'SPITE 6', and connector 7.
+
+A separate branch from connector 5 includes 'SPITE 4', 'SPITE 3', and state 05 (CONNECTED). From state 05:
+
+- BITE 22** leads to 'ANSWER (Note 3)'.
+- CLEAR-FORWARD** leads to 'FITE 22' and connector 6.
+- BITE 29** leads to connector 6.
+
+Flowchart of the Incoming INMARSAT Standard A signalling system (sheet 2 of 2).
+
+Note 2 - Includes also address translated from any received prefixes.
+
+Note 3 - If implemented.
+
+FIGURE B-3/Q.1101  
+(sheet 2 of 2)
+
+Incoming INMARSAT Standard A signalling system
+
+CCITT - 66041
+
+## ANNEX C
+
+(to Recommendation Q.1101)
+
+### **Logic procedures for outgoing INMARSAT Standard A signalling system (shore originated call)**
+
+This annex only includes those elements of the INMARSAT Standard A system which have to be implemented for interworking purposes.
+
+Internal procedures such as those required for setting-up and clearing of the satellite link are not shown. They are only included by task symbols.
+
+Other procedures not shown are:
+
+- interruption control procedures related to the satellite link;
+- pre-emption procedures for assigning channels to distress calls.
+
+For more details on the first generation INMARSAT Standard A signalling system, see Annex A.
+
+![State overview diagram for outgoing INMARSAT Standard A signalling system. It shows a sequence of states 00 to 06 with transitions between them. State 00 is Idle, 01 is Wait for CPCI Fite, 02 is Wait for Fite 1, 03 is Wait for continuity, 04 is Wait for clearing, 05 is Wait for answer, and 06 is Answered. Transitions are shown as arrows between states, with state 04 being a central node in a loop.](b90144cfbb81a2d610d920240fda689d_img.jpg)
+
+```
+
+    graph LR
+      00((00)) --> 01((01))
+      01 --> 02((02))
+      02 --> 03((03))
+      03 --> 04((04))
+      04 --> 05((05))
+      05 --> 06((06))
+      06 --> 04
+      04 --> 01
+      01 --> 00
+  
+```
+
+State overview diagram for outgoing INMARSAT Standard A signalling system. It shows a sequence of states 00 to 06 with transitions between them. State 00 is Idle, 01 is Wait for CPCI Fite, 02 is Wait for Fite 1, 03 is Wait for continuity, 04 is Wait for clearing, 05 is Wait for answer, and 06 is Answered. Transitions are shown as arrows between states, with state 04 being a central node in a loop.
+
+CCITT-59 720
+
+| <i>State number</i> | <i>State description</i> | <i>Sheet reference</i> |
+|---------------------|--------------------------|------------------------|
+| 00                  | Idle                     | 1                      |
+| 01                  | Wait for CPCI Fite       | 1                      |
+| 02                  | Wait for Fite 1          | 1                      |
+| 03                  | Wait for continuity      | 1                      |
+| 04                  | Wait for clearing        | 1                      |
+| 05                  | Wait for answer          | 1                      |
+| 06                  | Answered                 | 1                      |
+
+FIGURE C-1/Q.1101
+
+**State overview diagram for outgoing INMARSAT Standard A signalling system**
+
+FIGURE C-2/Q.1101
+
+(Reserved for future notes)
+
+![Flowchart of Outgoing INMARSAT Standard A signalling system. The process starts at IDLE (00), proceeds to ACTIVATE O/G INMARSAT, then WAIT FOR CPCI FITE (01). It then branches based on FITE signals (17, 18, 19, 22). If FITE 22 is received, it returns to IDLE (00). If FITE 17, 18, or 19 is received, it proceeds to WAIT FOR FITE 1 (02). From there, it checks for LAST DIGIT. If NO, it loops back to WAIT FOR FITE 1. If YES, it checks if SHIP BARRED. If YES, it sends BITE 20. If NO, it checks if SHIP BUSY. If YES, it sends BITE 16. If NO, it proceeds to SET-UP SATELLITE CHANNEL (part of the signalling procedure). Then it enters WAIT FOR CONTINUITY (03). From here, it branches based on signals: CONTINUITY (leads to BITE 5, then SPITE 6 CONNECT RINGING TONE), SHIP BUSY (leads to BITE 16), CONGESTION (leads to BITE 12), SHIP ABSENT (leads to BITE 20), CONTINUITY FAILURE (leads to BITE 17), or FITE 22 (leads to CLEAR-FORWARD). All these lead to a clearing procedure (CLEAR SATELLITE CHANNEL, WAIT FOR CLEARING (04), CHANNEL RELEASED, IDLE (00)). CONTINUITY leads to SPITE 6 CONNECT RINGING TONE, then WAIT FOR ANSWER (05). From WAIT FOR ANSWER, it branches to ANSWER (leads to SPITE 7 DISCONNECT RINGING TONE, then BITE 22, then connector 1) or FITE 22 (leads to connector 2). Connector 1 also leads to connector 2. Connector 2 leads to FITE 22 (part of the ANSWERED (06) sequence). The ANSWERED (06) sequence includes FITE 22 (leading to connector 2), CLEAR-BACK (leading to BITE 25, then connector 3), and connector 1.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+```
+
+graph TD
+    IDLE00_1((00 IDLE)) --> ACTIVATE[ACTIVATE O/G INMARSAT]
+    ACTIVATE --> WAIT01((01 WAIT FOR CPCI FITE))
+    WAIT01 --> FITE171819{FITE 17, 18, 19}
+    FITE171819 --> WAIT02((02 WAIT FOR FITE 1))
+    FITE171819 --> FITE22_1{FITE 22}
+    FITE22_1 --> IDLE00_2((00 IDLE))
+    WAIT02 --> LASTDIGIT{LAST DIGIT}
+    LASTDIGIT -- NO --> WAIT02
+    LASTDIGIT -- YES --> SHIPBARRED{IS SHIP BARRED}
+    SHIPBARRED -- YES --> BITE20_1{BITE 20}
+    SHIPBARRED -- NO --> SHIPBUSY{IS SHIP BUSY}
+    SHIPBUSY -- YES --> BITE16_1{BITE 16}
+    SHIPBUSY -- NO --> SETUP[SET-UP SATELLITE CHANNEL]
+    SETUP --> WAIT03((03 WAIT FOR CONTINUITY))
+    WAIT03 --> CONTINUITY{CONTINUITY}
+    WAIT03 --> SHIPBUSY_2{SHIP BUSY}
+    WAIT03 --> CONGESTION{CONGESTION}
+    WAIT03 --> SHIPABSENT{SHIP ABSENT}
+    WAIT03 --> CONTINUITYFAILURE{CONTINUITY FAILURE}
+    WAIT03 --> FITE22_2{FITE 22}
+    CONTINUITY --> BITE5{BITE 5}
+    BITE5 --> SPITE6[SPITE 6 CONNECT RINGING TONE]
+    SPITE6 --> WAIT05((05 WAIT FOR ANSWER))
+    WAIT05 --> ANSWER{ANSWER}
+    ANSWER --> SPITE7[SPITE 7 DISCONNECT RINGING TONE]
+    SPITE7 --> BITE22{BITE 22}
+    BITE22 --> C1_1((1))
+    SHIPBUSY_2 --> BITE16_2{BITE 16}
+    CONGESTION --> BITE12{BITE 12}
+    SHIPABSENT --> BITE20_2{BITE 20}
+    CONTINUITYFAILURE --> BITE17{BITE 17}
+    FITE22_2 --> CLEARFORWARD{CLEAR-FORWARD}
+    BITE16_2 --> CLEARPROC[Clearing procedure defined within the INMARSAT system]
+    BITE12 --> CLEARPROC
+    BITE20_2 --> CLEARPROC
+    BITE17 --> CLEARPROC
+    CLEARFORWARD --> C3_1((3))
+    CLEARPROC --> CLEARCHAN[CLEAR SATELLITE CHANNEL]
+    CLEARCHAN --> WAIT04((04 WAIT FOR CLEARING))
+    WAIT04 --> CHANNELREL[CHANNEL RELEASED]
+    CHANNELREL --> IDLE00_3((00 IDLE))
+    FITE22_2 --> FITE22_3{FITE 22}
+    FITE22_3 --> C2_1((2))
+    FITE22_3 --> CLEARBACK{CLEAR-BACK}
+    CLEARBACK --> BITE25{BITE 25}
+    BITE25 --> C3_2((3))
+    C1_1 --> C2_2((2))
+    C2_2 --> ANSWERED((06 ANSWERED))
+    ANSWERED --> FITE22_4{FITE 22}
+    FITE22_4 --> C2_3((2))
+    ANSWERED --> CLEARBACK_2{CLEAR-BACK}
+    CLEARBACK_2 --> BITE25_2{BITE 25}
+    BITE25_2 --> C3_3((3))
+    C1_1 --> C1_2((1))
+  
+```
+
+Flowchart of Outgoing INMARSAT Standard A signalling system. The process starts at IDLE (00), proceeds to ACTIVATE O/G INMARSAT, then WAIT FOR CPCI FITE (01). It then branches based on FITE signals (17, 18, 19, 22). If FITE 22 is received, it returns to IDLE (00). If FITE 17, 18, or 19 is received, it proceeds to WAIT FOR FITE 1 (02). From there, it checks for LAST DIGIT. If NO, it loops back to WAIT FOR FITE 1. If YES, it checks if SHIP BARRED. If YES, it sends BITE 20. If NO, it checks if SHIP BUSY. If YES, it sends BITE 16. If NO, it proceeds to SET-UP SATELLITE CHANNEL (part of the signalling procedure). Then it enters WAIT FOR CONTINUITY (03). From here, it branches based on signals: CONTINUITY (leads to BITE 5, then SPITE 6 CONNECT RINGING TONE), SHIP BUSY (leads to BITE 16), CONGESTION (leads to BITE 12), SHIP ABSENT (leads to BITE 20), CONTINUITY FAILURE (leads to BITE 17), or FITE 22 (leads to CLEAR-FORWARD). All these lead to a clearing procedure (CLEAR SATELLITE CHANNEL, WAIT FOR CLEARING (04), CHANNEL RELEASED, IDLE (00)). CONTINUITY leads to SPITE 6 CONNECT RINGING TONE, then WAIT FOR ANSWER (05). From WAIT FOR ANSWER, it branches to ANSWER (leads to SPITE 7 DISCONNECT RINGING TONE, then BITE 22, then connector 1) or FITE 22 (leads to connector 2). Connector 1 also leads to connector 2. Connector 2 leads to FITE 22 (part of the ANSWERED (06) sequence). The ANSWERED (06) sequence includes FITE 22 (leading to connector 2), CLEAR-BACK (leading to BITE 25, then connector 3), and connector 1.
+
+FIGURE C-3/Q.1101
+
+Outgoing INMARSAT Standard A signalling system
+
+## References
+
+- [1] Radio Regulations (Article 1, No. 71), ITU, Geneva, 1982.
+- [2] *Ibid.*, (Article 1, No. 73).

marked/Q/T-REC-Q.1151-199303-I_PDF-E/raw.md

@@ -0,0 +1,873 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**Q.1151**
+
+(03/93)
+
+**INTERWORKING WITH SATELLITE  
+MOBILE SYSTEMS**
+
+---
+
+**INTERFACES FOR INTERWORKING  
+BETWEEN THE INMARSAT AERONAUTICAL  
+MOBILE-SATELLITE SYSTEM AND  
+THE INTERNATIONAL PUBLIC SWITCHED  
+TELEPHONE NETWORK/ISDN**
+
+**ITU-T Recommendation Q.1151**
+
+(Previously "CCITT Recommendation")
+
+---
+
+# FOREWORD
+
+The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecommunication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+ITU-T Recommendation Q.1151 was revised by the ITU-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993).
+
+---
+
+# NOTES
+
+1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.
+
+In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms "CCITT, CCIR or IFRB" or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure.
+
+2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# CONTENTS
+
+*Page*
+
+|            |                                                                   |    |
+|------------|-------------------------------------------------------------------|----|
+| 1          | General .....                                                     | 1  |
+| 2          | Service capabilities.....                                         | 1  |
+| 2.1        | Channel capabilities.....                                         | 1  |
+| 2.2        | Bearer capabilities.....                                          | 2  |
+| 2.3        | Teleservices .....                                                | 2  |
+| 3          | Interworking scenarios .....                                      | 2  |
+| 4          | Connection interface requirements.....                            | 4  |
+| 4.1        | General.....                                                      | 4  |
+| 4.2        | MSSC-network interface .....                                      | 4  |
+| 4.3        | AES-MSSC interface.....                                           | 4  |
+| 4.4        | Calling procedures air-to-ground.....                             | 4  |
+| 4.5        | Calling procedures, ground-to-air.....                            | 5  |
+| 5          | Routing requirements .....                                        | 5  |
+| 5.1        | Ground originated calls.....                                      | 5  |
+| 5.2        | Aircraft originated calls .....                                   | 5  |
+| Appendix I | – INMARSAT aeronautical mobile-satellite system description ..... | 5  |
+| I.1        | Introduction .....                                                | 5  |
+| I.2        | System evolution .....                                            | 7  |
+| I.3        | Channel configuration .....                                       | 9  |
+| I.4        | Link layer formats and protocols .....                            | 10 |
+| I.5        | Aircraft earth station management.....                            | 11 |
+| I.6        | Telephone services.....                                           | 11 |
+
+
+
+# **INTERFACES FOR INTERWORKING BETWEEN THE INMARSAT AERONAUTICAL MOBILE-SATELLITE SYSTEM AND THE INTERNATIONAL PUBLIC SWITCHED TELEPHONE NETWORK/ISDN**
+
+*(Melbourne 1988, modified at Helsinki, 1993)*
+
+## **1 General**
+
+**1.1** This Recommendation provides information on the services offered in the INMARSAT aeronautical mobile-satellite system and describes the requirements for connection to and interworking with the public networks. Special terminology for this Recommendation is defined in Recommendation Q.1100. Detailed interworking procedures are set out in Recommendation Q.1152.
+
+**1.2** As well as connection to public networks, the aeronautical system is required to be able to interwork with existing specialized private networks. In implementing all interworking cases, regard should be paid to the open systems interconnection referenced model (X.200-Series Recommendations) and to ISDN services and signalling methods (I-Series Recommendations), with a view to achieving uniformity in user procedures and formats and to achieving generally applicable facilities.
+
+**1.3** Within the constraint of the need to operate as economically as possible, the preferred interworking cases are with the ISDN and with those parts of the international telephone network employing common channel signalling. If one of these is not available or accessible at the ISC to which an aeronautical ground earth station (GES) is connected then another signalling system from the Q-Series Recommendations should be used.
+
+**1.4** The use of the ISDN will offer both improvement in quality and more flexibility in service. It will be possible to supply either voice or data over the same network with the ability to change from one to the other under control of the aircraft earth station (AES) terminal.
+
+## **2 Service capabilities**
+
+A general description of the INMARSAT aeronautical system is contained in Appendix I.
+
+### **2.1 Channel capabilities**
+
+**2.1.1** The system provides circuit-mode single channel per carrier (SCPC) channels at a range of information bit rates, including at least the following:
+
+9600 bit/s; 4800 bit/s; 2400 bit/s
+
+Channels for other information bit rates, such as 64 000 bit/s, may be defined in the future.
+
+**2.1.2** The system provides demand assigned forward (ground to air) TDM channels and return (air to ground) random access and (reservation) TDMA channels, at a range of bit rates. Although the following bit rates include housekeeping overheads, they are indicative of the information bit rates provided:
+
+300 bit/s; 600 bit/s; 1200 bit/s; 2400 bit/s; 5250 bit/s.
+
+Channels for other bit rates may be defined in the future.
+
+### 2.2 Bearer capabilities
+
+2.2.1 The following bearer services on SCPC channels, with the following information transfer attributes as defined in Recommendation I.211, may be supported:
+
+- speech (initially at 9.6 kbit/s); transcoding to 64 kbit/s PCM should take place at the GES;
+- circuit mode audio service (initially at 9.6 kbit/s), suitable for voice and other signals occupying the same bandwidth; transcoding to 64 kbit/s PCM should take place at the GES;
+- virtual call bearer service at any of the bit rates defined in 2.1.1, with rate adaptation in the GES to 64 kbit/s using, for example, flow control and flag stuffing;
+- digital data, circuit mode interworking with the ISDN should take place as defined in Recommendation X.30 for data terminals designed to Recommendation X.21, and Recommendation X.32 for data terminals designed to Recommendation X.25.
+
+2.2.2 The following bearer services on TDM, TDMA and RA channels may be supported:
+
+- virtual call bearer service – interworking with the ISDN should take place as defined for interworking between PSPDNs and the ISDN.
+
+### 2.3 Teleservices
+
+Teleservices, when supported, should be in accordance with Recommendation I.212. It is to be observed that not all teleservices of ISDN may be supported with bearer services that can be provided on SCPC or TDM/TDMA channels operating at the available information bit rates.
+
+## 3 Interworking scenarios
+
+Three interworking scenarios can be envisaged for the interface between the MSSC and the fixed networks.
+
+3.1 The first scenario is shown in Figure 1. The MSSC public network interface is to the PSTN only, with all data services, and some voice services, handled via private networks.
+
+![Diagram of interworking scenario with PSTN interface. It shows a box labeled 'AES' connected to a box labeled 'GES' which is connected to a box labeled 'MSSC'. The 'MSSC' box is connected to a circle labeled 'PSTN' and a dashed line connects it to a circle labeled 'Private network'. Below the diagram is the text 'T1 155860-93/d01'.](47e8c2042061e08a14e012472e9fdbaa_img.jpg)
+
+```
+graph LR; AES[AES] --- GES[GES]; GES --- MSSC[MSSC]; MSSC --- PSTN((PSTN)); MSSC -.- PrivateNetwork((Private network));
+```
+
+T1 155860-93/d01
+
+Diagram of interworking scenario with PSTN interface. It shows a box labeled 'AES' connected to a box labeled 'GES' which is connected to a box labeled 'MSSC'. The 'MSSC' box is connected to a circle labeled 'PSTN' and a dashed line connects it to a circle labeled 'Private network'. Below the diagram is the text 'T1 155860-93/d01'.
+
+FIGURE 1/Q.1151  
+**Interworking scenario with PSTN interface**
+
+3.2 Figure 2 shows the situation where an ISDN exists and the MSSC has an interface to it. Interworking with the PSTN is achieved via the ISDN. Interworking with PDNs may be by direct interface with the PDN or via the ISDN, as in the case of the PSTN.
+
+![Diagram of interim interworking scenario with interfaces to ISDN and other fixed networks. It shows an AES connected to a GES, which is connected to an MSSC. The MSSC is connected to a PDN, which is connected to a PSTN. The MSSC is also connected to an ISDN. A Private network is shown with dashed lines connecting it to the MSSC, PDN, and ISDN.](fc46871d72c65d3381d9201646d23439_img.jpg)
+
+```
+
+graph LR
+    AES[AES] --- GES_MSSC[GES | MSSC]
+    GES_MSSC --- PDN((PDN))
+    GES_MSSC --- ISDN((ISDN))
+    PDN --- PSTN((PSTN))
+    GES_MSSC -.-> PN((Private network))
+    PDN -.-> PN
+    ISDN -.-> PN
+
+```
+
+T1155870-93/d02
+
+Diagram of interim interworking scenario with interfaces to ISDN and other fixed networks. It shows an AES connected to a GES, which is connected to an MSSC. The MSSC is connected to a PDN, which is connected to a PSTN. The MSSC is also connected to an ISDN. A Private network is shown with dashed lines connecting it to the MSSC, PDN, and ISDN.
+
+FIGURE 2/Q.1151  
+**Interim interworking scenario with interfaces  
+to ISDN and other fixed networks**
+
+In this scenario interworking with the ISDN supports speech, 3.1 kHz audio and data services as indicated in 2.2.1. Other bearer services as indicated in 2.2.2 may require interworking with PDNs.
+
+**3.3** The third scenario is shown in Figure 3. The MSSC interfaces to the ISDN, which provide data services as well as voice, although some voice and data services may still use private networks.
+
+![Diagram of interworking scenario with ISDN interface only. It shows an AES connected to a GES, which is connected to an MSSC. The MSSC is connected to an ISDN, which then connects to a PDN and a PSTN. A Private network is shown with dashed lines connecting it to the MSSC and ISDN.](49ee89a1d5852ab005dbbab6de09a8a6_img.jpg)
+
+```
+
+graph LR
+    AES[AES] --- GES_MSSC[GES | MSSC]
+    GES_MSSC --- ISDN((ISDN))
+    ISDN --- PDN((PDN))
+    ISDN --- PSTN((PSTN))
+    GES_MSSC -.-> PN((Private network))
+    ISDN -.-> PN
+
+```
+
+T1155880-93/d03
+
+Diagram of interworking scenario with ISDN interface only. It shows an AES connected to a GES, which is connected to an MSSC. The MSSC is connected to an ISDN, which then connects to a PDN and a PSTN. A Private network is shown with dashed lines connecting it to the MSSC and ISDN.
+
+FIGURE 3/Q.1151  
+**Interworking scenario with ISDN interface only**
+
+# 4 Connection interface requirements
+
+### 4.1 General
+
+This subclause identifies the information that must be available at the interfaces between the AES and the MSSC and between the MSSC and the fixed network, principally for the connection of services identified in 3.
+
+### 4.2 MSSC-network interface
+
+For ISDN connections ISUP should be used for message transfer. For non-ISDN or where ISUP is not available, TUP would be preferred.
+
+If information transport between MSSCs over the fixed network is required, it is suggested that the procedures of the SCCP is used. Detailed interworking procedures are defined in Recommendation Q.1152.
+
+### 4.3 AES-MSSC interface
+
+Prior to and during call initiation the signalling channel functions may be provided by one or more common control channels.
+
+A signalling capability should always be available during conversation in case it is needed for call clearing, call control, or for call management purposes. During a call the signalling channel may be multiplexed with the traffic channel at a lower bit rate so as to conserve radio channel capacity.
+
+The multiplexed signalling channel or TDM/TDMA/RA channels may be used for bearer services such as connectionless data services, or connection oriented data services not requiring the establishment of a traffic channel.
+
+The traffic channel should be used for bearer services such as:
+
+- speech;
+- circuit mode data services;
+- packet mode data services;
+- voice band data services.
+
+### 4.4 Calling procedures air-to-ground
+
+#### 4.4.1 Passenger telephony operation
+
+- a) The equipment for passenger telephony may consist of the following:
+  - the AES;
+  - cabin telephone equipment consisting of a fixed piece of equipment and a handset, which may be “cordless”.
+
+The fixed cabin telephone equipment should be provided with a credit card reader.
+
+- b) When a passenger wants to make a call, the typical sequence of events would be as follows:
+  - i) key-in seat number;
+  - ii) when this is accepted, insert credit card; and
+  - iii) when this is accepted, remove handset and return to seat.
+- c) At the cabin telephone location, if a credit card which corresponds to the recognized card format is inserted into the equipment, the handset shall be released after validation of the check bits and expiry date. In the event that either of these checks fail, the card shall be returned and the handset not released. Upon obtaining the handset the customer returns to his seat and can commence making one or more telephone calls.
+- d) Where telephones and associated credit card readers are located at the passengers' seats, a somewhat different procedure may apply. However, the procedure will still involve reading the credit card, validating the check bits and checking expiry date, before making calls.
+
+#### **4.4.2 Crew telephony operation**
+
+For this case, credit card validation procedures are not required. Crew will have access to special telephone services and networks, according to requirements and procedures developed by the industry. The capabilities will include at least the following:
+
+- a) access to the full public telephone network as for passengers, but without the need for a credit card (billing would be direct to the aircraft operator);
+- b) access to specialized voice services via private networks, with or without address digits;
+- c) ability to preempt an existing (passenger) call if necessary to make AES voice circuit equipment, a satellite channel or GES voice circuit equipment available;
+- d) ability to seize the next available AES voice circuit equipment, but without clearing any calls in progress.
+
+### **4.5 Calling procedures, ground-to-air**
+
+**4.5.1** Selected fixed network users should be able to access aircraft automatically by using the aircraft ID in the address digits. Operator connected access may also be available.
+
+**4.5.2** The numbering plan to enable a PSTN subscriber to call the AES is defined in Recommendation E.215.
+
+## **5 Routing requirements**
+
+### **5.1 Ground originated calls**
+
+The country code 87S should be analysed at all transit centres where the call may either be routed on a circuit containing a satellite link or on a circuit not containing a satellite link. The latter circuit should always be chosen (see Recommendation Q.14).
+
+### **5.2 Aircraft originated calls**
+
+If the signalling system provided between the MSSC and the terrestrial network contains signals which may be used to indicate that one satellite link is included, such signals should be used.
+
+If the signalling system does not contain such signals, the outgoing ISC should avoid forwarding the call on an outgoing circuit which includes a satellite link. If, however, the signalling system employed between the outgoing ISC and the next ISC in the connection contains such signals, the outgoing ISC should insert the required information. The outgoing ISC could base its procedure upon incoming route identification.
+
+# **Appendix I**
+
+## **INMARSAT aeronautical mobile-satellite system description**
+
+(This appendix does not form an integral part of this Recommendation)
+
+## **I.1 Introduction**
+
+The aeronautical satellite system is a mobile communications system intended for use by aircraft in flight. It can provide voice communication services and a range of data communications services.
+
+**I.1.1** The major elements of the aeronautical satellite system as described in this appendix are as follows (see also Figure I.1):
+
+- a) space segment, in particular the satellite communication transponders and associated frequency bands assigned for use by the aeronautical satellite system;
+- b) aircraft earth stations (AES) which are in accordance with the relevant technical requirements, and which interface with the space segment at L-band for communications with ground earth stations, and which interface in the aircraft with data equipment and with crew and passenger voice equipment;
+- c) aeronautical (ground) earth stations (GES) which interface with the space segment (at C-band and L-band) and with the fixed networks, and which are operated in accordance with the relevant technical and operational requirements for communications with AESs; for the “Initial System” GESs will operate to their own essentially independent networks; and
+- d) network coordination stations (NCS) located at designated earth stations, for the purpose of allocating satellite channels, and also for system control and monitoring; NCSs are planned to be introduced at a later stage as part of the “Enhanced System”.
+
+**I.1.2** The aeronautical system is made up of independent communication networks for each satellite ocean area, each network comprising the operational satellite and associated ground control facilities, the AESs and GESs operating within that area, and an NCS. The system design permits GESs to establish communications on a stand-alone basis with AESs without the intervention of the NCS, except in cases of satellite channel shortage.
+
+**I.1.3** Each AES is equipped with a capability to receive a medium rate forward channel transmitted from a GES with a transmission rate of 600 bit/s carrying signalling and data messages in packet form.
+
+**I.1.4** Each AES is equipped to transmit a return carrier in burst mode at a transmission rate of either 600 bit/s or 1200 bit/s controlled by signalling messages received via the forward 600 bit/s channel. This dual capability is required to enable some advantage of the variations in aircraft antenna pattern and in spacecraft receiver sensitivity, which will be encountered during a flight, to be taken.
+
+**I.1.5** AESs may also be equipped with pairs of transmit/receive voice channel equipment and data channel equipment for higher bit rates.
+
+**I.1.6** Each GES is equipped with at least the following data-only transmission capabilities:
+
+- a) one 600 bit/s transmitter for the forward channel;
+- b) four 600 bit/s receivers for the slotted random access channels (this is the minimum to be provided for diversity protection against interference, and burst re-collisions); and
+- c) a receiver for its 600 bit/s forward channel and for the forward channels of each other GES working to the same satellite.
+
+**I.1.7** At the GES owner's option, GESs may also be equipped with:
+
+- a) pairs of transmit/receive voice channel equipment;
+- b) 600 bit/s receiver(s) for a Reservation TDMA channel(s), or 600 bit/s and 1200 bit/s receiver(s) for Reservation TDMA channel(s); and
+- c) additional data channel equipment for the same or higher bit rates.
+
+**I.1.8** The system provides for voice communications by means of the voice channels. Signalling and user data communications is carried on the medium rate (600/1200 bit/s) data channels. This signalling and user data is formatted into fixed length signal units of either 96 bits (12 octets) or 152 bits (19 octets), which are combined as necessary to support various message sizes according to user requirements.
+
+## **I.2 System evolution**
+
+### **I.2.1 General**
+
+**I.2.1.1** The capabilities of the system will evolve with time, due to the progressive development of each of the four major elements identified in I.1.1 above, i.e. space segment, AES, GES and NCS. Although some of the evolutionary steps of one element are inevitably linked with those of other elements, in general the system concept is to allow the individual elements to evolve independently. The pressures which are expected to lead to this evolution include traffic growth, market awareness, new applications and new technology.
+
+**I.2.1.2** The use of narrow-band channels (generally single channel per carrier) and software programmable channel units (modems, etc.) are the principal requirements to achieve the required flexibility, to efficiently utilize a variety of satellite parameters, take advantage of future advances in voice coding technology, allow the aircraft installation to match the services required, and provide a smooth growth path from an initial start-up system through increasing levels of traffic.
+
+### **I.2.2 Space segment evolution**
+
+**I.2.2.1** Within the aeronautical system operational timeframe, it is anticipated that the satellite types of INMARSAT's first generation space segment still in service will comprise MARECS (leased from the European Space Agency) and INTELSAT-V MCS satellites (Maritime Communications Sub-System, leased from the International Telecommunications Satellite Organization). Satellite tracking, telecommand, telemetry and ranging services are included in the leasing arrangements with ESA and INTELSAT, with TT&C stations linked to satellite control centres (SCCs) at Darmstadt (Germany) and Washington DC, respectively. The SCCs are in turn linked to the INMARSAT Operations Control Centre (OCC) in London.
+
+**I.2.2.2** The aeronautical system will also operate with and take advantage of the improved performance of the (second generation) INMARSAT-2 satellites, now on order.
+
+### **I.2.3 AES evolution**
+
+**I.2.3.1** Two types of aircraft antenna are defined, one with a minimum gain of 0 dBi over its coverage area, the other with a minimum gain of 12 dBi over its coverage area. In the initial system, AESs with the 0 dBi antenna are limited to medium rate data services (see I.2.4.2), while AESs with the 12 dBi antenna can obtain multi-channel voice service as well as data services at higher bit rates.
+
+**I.2.3.2** Irrespective of the antenna gain, each AES is required to be equipped with a bit rate switchable data channel unit. The minimum capability is to provide for both 600 bit/s and 1200 bit/s transmission rates (300 bit/s and 600 bit/s information rate, less overheads) and this will suffice for the initial two or three years. Additional, higher bit rates will be needed in the future and these could be provided for in the initial AES design, or be achieved by a software upgrade in a programmable channel unit, or by replacement of a plug-in card.
+
+**I.2.3.3** In operation, the bit rate in use by the AES for data services is determined by signalling from the ground. When commencing service with a given GES, an AES goes through a "log-on" procedure, using the 600 bit/s transmission rate channels assigned for system management (and possibly other) functions. In this log-on procedure, the AES gives its class of equipment provision, and the GES measures the signal level received from the AES if needed, to determine whether a higher bit rate could be supported. From this information the GES assigns working channels for further signalling and data transactions with the AES.
+
+**I.2.3.4** Since the other elements of the system will evolve with time, the AES capabilities have been defined in a way which provides adequate service levels in the start-up phases, but which can take advantage of improved performance in the other elements as they become available, without requiring any significant replacement or upgrade of components. Specifically, the AES is specified with a linear high power amplifier (HPA) with a power output of 40 Watts, and a family of digital channels is defined which are all mutually consistent and compatible.
+
+This makes it feasible to use a single programmable channel unit [using digital signal processor (DSP) microprocessor chips] to implement a suitable selection of channel types from the family, and allow for additional or alternative channel types in the future if required, by software upgrade. The linear characteristic of the HPA permits matching the evolution
+
+of space segment characteristics, providing progressively greater numbers of voice channels with higher performance spacecraft, and also allowing the separation of services in different GESs if required in the future [such as dedicated GESs for air traffic services (ATS)].
+
+**I.2.3.5** It may be anticipated that the service requirements and technology applied to them on aircraft will develop independently of satellite communications. Examples of this type of development are data applications such as for monitoring of equipment health, and the progressive reduction of digital bit rate needed to provide voice service of a given quality. This system makes specific provision for evolution in voice coding, and by adopting a layered approach, along the lines defined in the Open System Interconnection (OSI) model, facilitates its use for as yet unforeseen data applications. In addition, there is ample provision of spare codes in the critical signalling fields, so that if enhancements become necessary they can be implemented by software upgrades.
+
+**I.2.3.6** Although the AES is specified to use a linear HPA, the offset QPSK modulation method is used in the higher bit rate channels in order to make operation with a hard limiting linear (e.g. Class C) HPA feasible. This will permit the development of single-channel AES equipment suitable for general aviation aircraft, when a demand develops.
+
+### **I.2.4 GES evolution**
+
+**I.2.4.1** The aeronautical GES has been defined so it can be produced as a compatible add-on to an existing standard coast earth station in the INMARSAT system. While this type of sharing is not essential, it may enable some economies to be achieved particularly in the start-up phase of the system, and where both services are carried by the same satellite.
+
+**I.2.4.2** As new satellites become available and traffic grows, the data transmission bit rates which can be supported, and need to be supported, will increase. To achieve this, additional data channel units, and/or higher bit rate channel units, will need to be provided at the GESs. The system can operate exclusively with data channel bit rates of 600 bit/s, and this may be sufficient in the initial stage. However, higher bit rates in the return direction (air-to-ground) can be supported even from a 0 dBi antenna, except at edge of coverage with existing (first generation) spacecraft, and will be able to be supported globally with INMARSAT-2 satellites. Thus the provision of higher bit rate channel units by the late 1980s will be appropriate, to provide for growing traffic and to minimize data service message delays. Depending on demand, it may also be appropriate to provide data channel units for interworking with aircraft fitted with 12 dBi antennas. Since all the channels form a compatible family, the possibility exists of using a common hardware unit for all these channels, differing only in software.
+
+**I.2.4.3** To take advantage of evolution in voice coding technology, it may be anticipated that a point will be reached when the voice coding rate and algorithm used in the initial system will be considered inappropriate, at least for new aircraft installations. A decision to adopt new voice coding rate will be practicable, the main requirement being that GESs wishing to interwork with all aircraft will need to operate two sets of channel units and associated voice codecs. As for data, the channel unit hardware could be common, although the voice codecs may be of different designs.
+
+### **I.2.5 NCS evolution**
+
+**I.2.5.1** The function of the NCS is to manage a common pool of satellite voice channels, and to assign them on demand to individual GESs for the duration of one call. In a system with small capacity and multiple GESs the random distribution of traffic across GESs necessitates the provision of a common pool managed by an NCS, for efficiency reasons. When traffic is low in the initial start-up phase, operation with only individual pools of channels at each GES will be satisfactory, but as additional GESs come into service the NCS will become essential.
+
+**I.2.5.2** In the initial system operating without an NCS, communication between GESs is still required to allow aircraft to call or be called via more than one GES. This communication is achieved by using a forward channel from each GES; the channel could be the one also designated for system management functions, or a separate, lower powered channel. In any case the implementation should be arranged so as to facilitate a changeover to a separate interstation link and the provision of an NCS, in the long term.
+
+## I.3 Channel configuration
+
+### I.3.1 General
+
+**I.3.1.1** The basic transmission characteristics of the family of aeronautical system channels are given in Table I.1. The channel bit rates have been selected to facilitate their implementation using a single programmable channel unit and to provide future flexibility. While this may not be practicable now for the highest bit rates in the table, future implementations may be able to take advantage of this structure.
+
+TABLE I.1/Q.1151
+
+#### Channel transmission characteristics summary
+
+| Bearer rate (bit/s) | Channel rate (bit/s) | Channel spacing (kHz) | Modulation |
+|---------------------|----------------------|-----------------------|------------|
+| 9600                | 21 000               | 17.5                  | O-QPSK     |
+| 9600                | 10 500               | 10.0                  | O-QPSK     |
+| 5250 <sup>a)</sup>  | 10 500               | 10.0                  | O-QPSK     |
+| 4800                | 5 250                | 5.0                   | O-QPSK     |
+| 2400                | 6 000                | 5.0                   | O-QPSK     |
+| 2400 <sup>a)</sup>  | 4 800                | 5.0                   | O-QPSK     |
+| 1200 <sup>a)</sup>  | 2 400                | 5.0                   | DECPSK     |
+| 600 <sup>a)</sup>   | 1 200                | 5.0                   | DECPSK     |
+| 300 <sup>a)</sup>   | 600                  | 5.0                   | DECPSK     |
+
+a) Less overheads.
+
+### I.3.2 Channel naming
+
+In order to simplify references to the various channel formats included in the system, each individual format has been assigned a designation as follows (see also Figure I.1):
+
+#### a) *P-Channel*
+
+Packet mode time division multiplex (TDM) channel, used in the forward direction (ground-to-air) to carry signalling and user data; the transmission is continuous from one GES; a P-channel being used for system management functions is designated Psmc, while a P-channel being used for other functions is designated Pd;
+
+#### b) *R-Channel*
+
+Random access (slotted ALOHA) channel, used in the return direction (aircraft-to-ground) to carry some signalling and user data, specifically the initial signals of a transaction, typically request signals; an R-channel being used for system management functions is designated Rsmc, while an R-channel being used for other functions is designated Rd;
+
+#### c) *T-Channel*
+
+Reservation Time Division Multiple Access channel, used in the return direction only; the receiving GES reserves time slots for transmissions requested by AESs, according to message lengths and priority;
+
+#### d) *C-Channel*
+
+Circuit-mode single channel per carrier (SCPC) voice/data channel, used in both forward and return directions; the use of the channel is controlled by assignment and release signalling at the start and end of each call.
+
+![Diagram of Aeronautical network configuration showing data flow between Communications terminals, Aircraft earth station (AES), Aeronautical Ground earth station (GES), and Terrestrial networks. It details P, R, T, and C channels with their respective signaling and data rates.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+```
+
+graph LR
+    CT[Communications terminals] <--> AES[Aircraft earth station - AES]
+    AES -- "P-Channel" --> GES[Aeronautical Ground earth station - GES]
+    AES -- "R-Channel" --> GES
+    AES -- "T-Channel" --> GES
+    AES <--> "C-Channel (Voice + data-high rate)" <--> GES
+    GES <--> TN[Terrestrial networks]
+    OtherGES[P-Channel(s) from other GES] --> GES
+
+    subgraph "Signalling + data-medium rate"
+    P-Channel
+    R-Channel
+    T-Channel
+    end
+
+```
+
+P-Channel Packet mode channel  
+R-Channel Slotted random access (ALOHA) channel  
+C-Channel Circuit mode channel  
+T-Channel Reservation TDMA channel
+
+Diagram of Aeronautical network configuration showing data flow between Communications terminals, Aircraft earth station (AES), Aeronautical Ground earth station (GES), and Terrestrial networks. It details P, R, T, and C channels with their respective signaling and data rates.
+
+FIGURE I.1/Q.1151  
+**Aeronautical network configuration**
+
+### I.3.3 Forward error correction coding
+
+The majority of channel types use Forward Error Correction (FEC) coding consisting of a convolutional encoder of constraint length  $k = 7$  and an 8-level soft decision Viterbi decoder; the FEC coding rate is either  $3/4$  or  $1/2$ ; the rate  $3/4$  code is derived by puncturing the rate  $1/2$ ,  $k = 7$  convolutional code.
+
+## I.4 Link layer formats and protocols
+
+#### I.4.1 General
+
+All signalling and user data messages are formatted into signal units of length either 96 bits (12 octets) or 152 bits (19 octets). The extended length signal units (19 octets) are only used on the R-channel, whereas the standard length signal units (12 octets) are used on all channels.
+
+More complex messages (including user data) can be carried by a sequence of several signal units. Longer messages generated in a user application will be broken into message fragments in the network layer, compatible with the maximum size, before being presented for transmission via the link layer; the use of these signal units applies to signalling and user data transactions on the sub-band channel of the voice/data channel as well as the P-, R- and T-channels.
+
+### I.4.2 Basic signal unit concepts
+
+**I.4.2.1** A message that can be accommodated in a single signal unit is formatted into a “Lone Signal Unit” (LSU). Longer messages are formatted into more than one signal unit, of which the first is an “Initial Signal Unit” (ISU) followed by one or more “Subsequent Signal Units” (SSU).
+
+**I.4.2.2** Each signal unit includes 16 check bits (the last two octets) for error detection, these being calculated from the preceding octets of the signal unit using the polynomial:  $x^{16} + x^{12} + x^5 + 1$  for generation (see 2.2.7/X.25). The undetected error rate on the sub-band C-channel, under nominal worst case conditions is typically less than one in  $10^{10}$  signal units. The undetected error rate on P- and R-channels is expected to be much less than this.
+
+**I.4.2.3** At the receiver for any channel, the check bits for each received signal unit are calculated, and if there is a mismatch with the received check bits the signal unit is discarded. Recovery from lost and corrupted signal units is handled either by a Reliable Link Service function, or by the relevant signalling logic procedures.
+
+## **I.5 Aircraft earth station management**
+
+**I.5.1** Every GES maintains an up-to-date status table of AESs which have logged into the GES, and has an inter-GES and GES-NCS signalling facility, so that every GES shall be able to set up calls to and from any AES operating to the same satellite, and to manage AESs in the handover process.
+
+**I.5.2** Every AES logs-on to a GES of its choice for entering into the Aeronautical system and logs-out as part of terminating its operation in the system. When an AES requires a change in its log-in GES, accessing satellite or accessing spot beam of a satellite, the AES follows a handover procedure resulting in a smooth transition.
+
+## **I.6 Telephone services**
+
+### **I.6.1 General**
+
+**I.6.1.1** Telephone services are provided using a pair of C-channels (one in each direction) assigned from a pool held by the GES, or by the NCS from a common pool. The function of the NCS is to make C-channel assignments in response to requests from GESs (when the latter runs out of frequencies) on a call-by-call basis.
+
+**I.6.1.2** In the ground-to-air direction, all telephone calls may go to a single answering point on the aircraft, or may be addressed to specific answering points. In the initial system at least, for commercial aircraft, access will be restricted to a very limited number of callers for operational and practical reasons. This restriction will be imposed in the GES, or elsewhere, at the discretion of the GES owner.
+
+**I.6.1.3** In the air-to-ground direction, calls may be made by crew or passengers, with several types of service provided. The primary service capabilities include:
+
+- a) passenger telephony;
+- b) crew general telephony; and
+- c) crew ATC voice.
+
+### **I.6.2 Call set-up/termination for air-to-ground calls**
+
+**I.6.2.1** The basic sequences for air-to-ground telephone call set-up are shown in Figures I.2 to I.5, covering various cases including use of an NCS.
+
+**I.6.2.2** From the point of view of the AES, all the cases are the same, with the AES receiving the called number (and in the case of passenger calls the credit card data) prior to starting the request process. An initial request is sent using the R-channel to the GES where the AES is logged in, and a channel assignment is received on the corresponding P-channel. The communications channel is then set up, tested using signals on the sub-band data channel, and the called party address (plus the credit card number if applicable) is transmitted via the sub-band data channel.
+
+**I.6.2.3** If the air-to-ground call is to the log-on GES (Figure I.2), then all the access request and channel assignment transactions are carried via the R- and P-channels only. However, if the call is to a GES other than the one where the AES logged-on (Figure I.3), then the log-on GES forwards the access request (from the AES) to the called GES (designated "other" GES in Figure I.3) over the interstation link. The called GES allots a channel, if available, from its pool and transmits the channel assignment information over the interstation link. The log-on GES then forwards the information to the AES over the P-channel. The corresponding signalling sequences for air-to-ground call set-up using the NCS are shown in Figures I.4 and I.5, the former representing the case of a call addressed to a log-on GES and the latter showing a call addressed to a GES other than the one where the AES has logged- on.
+
+In the former case (Figure I.4), the log-on GES, on receipt of an access request from the AES, sends a Request for Assignment message over the interstation link to the NCS, whereupon the NCS responds by sending a channel assignment to the requesting GES over the same interstation link. The GES sends this channel assignment to the AES over the P-channel.
+
+In the case of a call addressed to "other" GES, the procedure is similar to the above, with the addition of the log-on GES as an intermediary between the AES and "other" GES. After the call is cleared, the GES to which the channel is assigned by the NCS (i.e the "other" GES), sends the channel release information to the NCS over the interstation link. The transaction is completed by the NCS sending an acknowledgement to the GES.
+
+In the normal case, when the call is ended both parties will replace their handsets (abnormal cases are covered in Figure I-6 and Recommendation Q.1152). The on-hook condition of the telephone in the AES initiates a series of channel release signals on the sub-band C-channel. When one of these is received in the GES, it monitors the carrier to confirm that it stops. If the AES is logged-on to another GES, the channel release signal is sent to the log-on GES via the appropriate interstation link.
+
+![Sequence diagram showing the air-to-ground telephone call set-up sequence between a Ground Station (GES) and an Aircraft Station (AES).](5cab96b2d23174c25919840ecd50aa48_img.jpg)
+
+```
+
+sequenceDiagram
+    participant GES
+    participant AES
+    Note right of AES: Credit card data
+    Note right of AES: (User) Off-hook & number
+    Note right of AES: Access request
+    Note right of AES: Service address and credit card data (if applicable)
+    Note right of AES: (Continuous)
+    Note right of AES: Connect through
+    Note right of AES: Service address and credit card data stopped
+    Note right of AES: Acknowledge
+
+    AES->>GES: Rd
+    GES->>AES: Pd
+    GES->>AES: C, sub-band
+    Note left of GES: C-channel assignment
+    Note left of GES: Test signal units (continuous)
+    Note left of GES: When call inform. complete, test signals stopped
+    Note left of GES: Call attempt result (address complete)
+    Note left of GES: Connect through
+    
+```
+
+The diagram illustrates the call set-up sequence between a Ground Station (GES) and an Aircraft Station (AES). The sequence begins with the AES sending 'Credit card data', '(User) Off-hook & number', and an 'Access request' to the GES. The GES responds with 'Rd' (Request data) and 'Pd' (Provide data). The GES then sends a 'C-channel assignment' and 'Test signal units (continuous)' on the 'C, sub-band'. The AES replies with 'Service address and credit card data (if applicable)'. The GES continues with 'C, sub-band' signals. Once the call information is complete, the test signals stop, and the GES sends a 'Call attempt result (address complete)'. The AES responds with '(Continuous)', 'Connect through', 'Service address and credit card data stopped', and an 'Acknowledge'. The GES completes the 'Connect through' phase.
+
+T1128290-90/d05
+
+Rd See 1.3.2  
+Pd See 1.3.2
+
+Sequence diagram showing the air-to-ground telephone call set-up sequence between a Ground Station (GES) and an Aircraft Station (AES).
+
+FIGURE I.2/Q.1151  
+Air-to-ground telephone call set-up sequence
+
+![Sequence diagram showing air-to-ground telephone call set-up sequence between 'Other' GES, Log-on GES, and AES. The sequence includes messages like Credit card data, (User) Off-hook & number, Access request, Rd, Interstation link, C-channel assignment, Pd, Service address and credit card data (if applicable) (continuous), and Test signal units (continuous).](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AES
+    participant Log-on GES
+    participant Other_GES as "Other" GES
+
+    Note right of AES: Credit card data
+    Note right of AES: (User) Off-hook & number
+    AES->>Log-on GES: Access request
+    Log-on GES-->>AES: Rd
+    Log-on GES->>Other_GES: Interstation link
+    Other_GES-->>Log-on GES: C-channel assignment
+    Log-on GES-->>AES: Pd
+    AES->>Log-on GES: Service address and credit card data (if applicable) (continuous)
+    Log-on GES-->>Other_GES: C, sub-band
+    Other_GES-->>Log-on GES: Test signal units (continuous)
+    Log-on GES-->>AES: C, sub-band
+  
+```
+
+Sequence diagram showing air-to-ground telephone call set-up sequence between 'Other' GES, Log-on GES, and AES. The sequence includes messages like Credit card data, (User) Off-hook & number, Access request, Rd, Interstation link, C-channel assignment, Pd, Service address and credit card data (if applicable) (continuous), and Test signal units (continuous).
+
+T1128300-90/d06
+
+Further procedure is same as for air-to-ground call setup for the log-on GES
+
+Rd See 1.3.2
+
+Pd See 1.3.2
+
+FIGURE I.3/Q.1151
+
+**Air-to-ground telephone call set-up sequence to other GES**
+
+![Sequence diagram showing the air-to-ground telephone call set-up sequence (overflow mode) between NCS, Log-on GES, and AES. The sequence includes messages like Credit card data, (User) Off-hook & number, Access request, Rd, Req. for C-channel, Interstation link, C-channel assignment, Pd, C, sub-band, Test signal units (continuous), C-channel release, and C-channel release ack.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+```
+
+sequenceDiagram
+    participant NCS
+    participant Log-on GES
+    participant AES
+
+    Note right of AES: Credit card data
+    Note right of AES: (User) Off-hook & number
+    Note right of AES: Access request
+    AES->>Log-on GES: Rd
+    Note right of Log-on GES: Req. for C-channel
+    Log-on GES->>NCS: Interstation link
+    Note left of NCS: C-channel assignment
+    NCS->>Log-on GES: C-channel assignment
+    Log-on GES->>AES: Pd
+    Note right of AES: Service address and credit card data (if applicable) (continuous)
+    AES->>Log-on GES: C, sub-band
+    Note left of Log-on GES: Test signal units (continuous)
+    Log-on GES->>AES: C, sub-band
+    Log-on GES->>NCS: C-channel release
+    Note left of NCS: C-channel release ack.
+    NCS->>Log-on GES: 
+  
+```
+
+Sequence diagram showing the air-to-ground telephone call set-up sequence (overflow mode) between NCS, Log-on GES, and AES. The sequence includes messages like Credit card data, (User) Off-hook & number, Access request, Rd, Req. for C-channel, Interstation link, C-channel assignment, Pd, C, sub-band, Test signal units (continuous), C-channel release, and C-channel release ack.
+
+T1128310-90/d07
+
+Further procedure is same as for air to ground call without NCS till GES monitors for carrier off after clearing
+
+Rd See 1.3.2
+
+Pd See 1.3.2
+
+FIGURE 1.4/Q.1151
+
+**Air-to-ground telephone call set-up sequence (overflow mode)**
+
+![Sequence diagram for Air-to-ground telephone call set-up sequence to other GES (overflow mode).](9c6461e1e94afae4dec455e69a2ce152_img.jpg)
+
+The diagram illustrates the call set-up sequence between four entities: "Other" GES, NCS, Log-on GES, and AES. The sequence of messages is as follows:
+
+- Request for channel assignment:** The Log-on GES sends an **Rd** message to the AES. The AES responds with **Credit card data**, **(User) Off-hook & number**, and **Access request**. The Log-on GES then sends an **Access request** to the NCS. The NCS sends an **ISL** message to the "Other" GES. The "Other" GES responds with an **ISL** message to the NCS. The NCS sends a **C-channel assign.** message to the Log-on GES.
+- C-channel assign.:** The Log-on GES sends a **Pd** message to the AES. The AES responds with **Services address & credit card data (if applicable) (continuous)**. The Log-on GES sends a **C-channel assign.** message to the NCS. The NCS sends a **C, sub-band** message to the Log-on GES. The Log-on GES sends a **C, sub-band** message to the AES.
+- Test signal units (continuous):** The Log-on GES sends a **C, sub-band** message to the NCS. The NCS sends a **C, sub-band** message to the Log-on GES. The Log-on GES sends a **C, sub-band** message to the AES.
+- C-channel release:** The Log-on GES sends an **ISL** message to the NCS. The NCS responds with an **ISL** message to the Log-on GES. The Log-on GES sends an **ISL** message to the "Other" GES. The "Other" GES responds with an **ISL** message to the Log-on GES. The Log-on GES sends a **C-channel release ack.** message to the NCS.
+
+Sequence diagram for Air-to-ground telephone call set-up sequence to other GES (overflow mode).
+
+T1128320-90/d08
+
+Further procedure is same as for air to ground call without NCS  
+till GES monitors carrier off after clearing
+
+ISL Interstation link
+
+Rd See 1.3.2
+
+Pd See 1.3.2
+
+FIGURE I.5/Q.1151
+
+**Air-to-ground telephone call set-up sequence to other GES (overflow mode)**
+
+![Sequence diagram of Air-to-ground telephone call user switchhook signalling between GES and AES.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg)
+
+The diagram illustrates the signalling sequence between a Ground Station (GES) and an Air Station (AES) for an air-to-ground call. The sequence starts with the B-party off-hook (Answer) at the GES, followed by a Connect signal. The GES then sends a series of 'C, sub-band' signals to the AES, which responds with an 'Acknowledge'. The GES then sends a 'B-party on-hook (Clearback)' signal, followed by 'Time supervision of 1 to 2 minutes'. The GES then sends a 'Channel release<sup>a)</sup> then carrier off' signal, which the AES acknowledges with 'Channel release<sup>a)</sup> then carrier off'. The GES monitors for carrier off and sends a 'Clearback sequence'. The AES then sends an '(A-Party) On-hook' signal, followed by 'Channel release<sup>a)</sup> then carrier off' and 'Carrier off'. The GES monitors for carrier off again.
+
+Sequence of events:
+
+- B-party off-hook (Answer) → GES
+- Connect → GES
+- C, sub-band → AES
+- Acknowledge → AES
+- A: Answer sequence (dashed line)
+- B-party on-hook (Clearback) → GES
+- Time supervision of 1 to 2 minutes (dashed line)
+- C, sub-band → AES
+- Channel release<sup>a)</sup> then carrier off → AES
+- C, sub-band → GES
+- GES monitors for carrier off (dashed line)
+- B: Clearback sequence (dashed line)
+- (A-Party) On-hook → AES
+- Channel release<sup>a)</sup> then carrier off → AES
+- Carrier off → AES
+- C, sub-band → GES
+- GES monitors for carrier off (dashed line)
+
+Sequence diagram of Air-to-ground telephone call user switchhook signalling between GES and AES.
+
+T1128330-90/d09
+
+C: Clearing sequence
+
+<sup>a)</sup> Repeated 6 times.
+
+FIGURE I.6/Q.1151  
+Air-to-ground telephone call user switchhook signalling
+
+### I.6.3 Channel set-up/termination for ground-to-air calls
+
+**I.6.3.1** The sequences for ground-to-air telephone call set-up are shown in Figures I.7 to I.10 covering various cases, including use of an NCS.
+
+**I.6.3.2** From the viewpoint of the AES, all the cases are similar with the GES sending the call announcement and channel assignment information to the AES over the P-channel. After the channel assignment information is transferred to the AES, the continuity check for proper channel set-up and the eventual channel release functions of the satellite link, are carried out using signals on the sub-band C-channel.
+
+**I.6.3.3** In the case of a call from a log-on GES to an AES (Figure I.7) the only channel used prior to setting up the call is the P-channel. However, if the call is from a GES other than where the AES has logged-on (Figure I.8) the originating GES (“other” GES) sends the call announcement and channel assignment information to the log-on GES over the interstation link. The log-on GES then forwards this information to the AES over the P-channel. The signalling sequences for the cases where the call- originating GES does not have a channel in its allocated pool are shown in Figures I.9 and I.10, the former showing the case of a call originating from a log-on GES and the latter representing a call origination from a GES other than the one to which the AES has logged-on. In both cases the interstation link between the NCS and the call originating GES is used to obtain a channel from the NCS pool. After the call is cleared, the GES from which the call has originated, sends the channel release information to the NCS, which the NCS acknowledges. The procedure for call clearing (illustrated in Figure I.11) is initiated by the terrestrial network sending a clear forward signal, whereupon the GES sends a sequence of channel release signals on the sub-band C-channel. On receipt of one of these, the AES responds with a series of channel release signals, and ceases its carrier. When the GES detects the end of the AES carrier, it returns the channel to the pool.
+
+![Sequence diagram for Ground-to-air telephone call set-up sequence between GES and AES.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg)
+
+This sequence diagram illustrates the call set-up between a Ground Station (GES) and an Air Station (AES). The sequence begins with an external 'Call' arriving at the GES. The GES sends a 'Call announcement' (Pd) and a 'C-channel announcement' (Pd) to the AES. The AES responds with 'Test signal units (continuous)'. The GES replies with two 'C, sub-band' messages and also sends its own 'Test signal units (continuous)'. The AES then initiates the 'Call to user terminal' and sends a 'Test signals stopped' message. Finally, the GES sends a 'Connect through' message, leading to 'Ring tone or alerting' at the user terminal.
+
+```
+
+sequenceDiagram
+    participant External
+    participant GES
+    participant AES
+    Note left of GES: Pd See 1.3.2
+    External->>GES: Call
+    GES->>AES: Call announcement (Pd)
+    GES->>AES: C-channel announcement (Pd)
+    AES->>GES: Test signal units (continuous)
+    GES->>AES: C, sub-band
+    GES->>GES: Test signal units (continuous)
+    GES->>AES: C, sub-band
+    AES->>External: Call to user terminal
+    AES->>GES: Test signals stopped
+    GES->>External: Connect through
+    External->>External: Ring tone or alerting
+  
+```
+
+Sequence diagram for Ground-to-air telephone call set-up sequence between GES and AES.
+
+T1128340-90/d10
+
+Pd See 1.3.2
+
+FIGURE I.7/Q.1151  
+Ground-to-air telephone call set-up sequence
+
+![Sequence diagram for Ground-to-air call set-up sequence via other GES, involving 'Other' GES, Log-on GES, and AES.](a3472689858b068ef469213682965325_img.jpg)
+
+This sequence diagram shows the call set-up process involving three entities: 'Other' GES, Log-on GES, and AES. An external 'Call' arrives at the 'Other' GES, which sends a 'Call announcement' and a 'C-channel assignment' to the Log-on GES. The Log-on GES then sends a 'Pd' message and 'Test signal units (continuous)' to the AES. The AES responds with 'C, sub-band' and 'Test signal units (continuous)'. The Log-on GES receives a 'C, sub-band' from the AES and forwards it to the 'Other' GES. The Log-on GES also sends 'Test signals stopped' to the AES. Finally, the Log-on GES sends a 'Connect through' message to the 'Other' GES, resulting in 'Ring tone or alerting' at the user terminal.
+
+```
+
+sequenceDiagram
+    participant External
+    participant OtherGES as "Other" GES
+    participant LogonGES as Log-on GES
+    participant AES
+    Note left of OtherGES: Pd See 1.3.2
+    External->>OtherGES: Call
+    OtherGES->>LogonGES: Call announcement
+    OtherGES->>LogonGES: C-channel assignment
+    LogonGES->>AES: Pd
+    LogonGES->>AES: Test signal units (continuous)
+    AES->>LogonGES: C, sub-band
+    AES->>AES: Test signal units (continuous)
+    LogonGES->>OtherGES: C, sub-band
+    LogonGES->>AES: Test signals stopped
+    LogonGES->>OtherGES: Connect through
+    OtherGES->>External: Ring tone or alerting
+  
+```
+
+Sequence diagram for Ground-to-air call set-up sequence via other GES, involving 'Other' GES, Log-on GES, and AES.
+
+T1128350-90/d11
+
+Pd See 1.3.2
+
+FIGURE I.8/Q.1151  
+Ground-to-air call set-up sequence via other GES
+
+![Sequence diagram showing the ground-to-air telephone call set-up sequence (overflow mode) between GES, NCS, and AES.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg)
+
+```
+
+sequenceDiagram
+    participant GES
+    participant NCS
+    participant AES
+
+    Note over GES: Call
+    GES->>NCS: Request for channel assignment (ISL)
+    NCS-->>GES: C-channel assignment
+    GES->>AES: Call announcement (Pd)
+    GES->>AES: C-channel assignment (Pd)
+    AES-->>GES: Test signal units (continuous) (C, sub-band)
+    GES-->>AES: Test signal units (continuous) (C, sub-band)
+    GES->>NCS: C-channel release (ISL)
+    NCS-->>GES: C-channel release ack. (ISL)
+  
+```
+
+The diagram illustrates the call set-up sequence for a ground-to-air telephone call in overflow mode. It involves three main entities: GES (Ground Earth Station), NCS (Network Coordination Station), and AES (Aircraft Earth Station). The sequence begins with an incoming 'Call' at the GES. The GES sends a 'Request for channel assignment' via an Interstation link (ISL) to the NCS. The NCS responds with a 'C-channel assignment'. The GES then sends a 'Call announcement' and 'C-channel assignment' (both marked Pd) to the AES. Continuous 'Test signal units' are then exchanged between the AES and GES on the C, sub-band. Finally, the GES sends a 'C-channel release' (ISL) to the NCS, which acknowledges it with a 'C-channel release ack.' (ISL).
+
+Sequence diagram showing the ground-to-air telephone call set-up sequence (overflow mode) between GES, NCS, and AES.
+
+T1128360-90/d12
+
+Further procedure is same as for air to ground call without NCS till GES monitors carrier off after clearing
+
+ISL Interstation link  
+Pd See 1.3.2
+
+FIGURE I.9/Q.1151  
+**Ground-to-air telephone call set-up sequence (overflow mode)**
+
+![Sequence diagram showing ground-to-air telephone call set-up sequence via other GES (overflow mode). Lifelines: Call, 'Other' GES, NCS, Log-on GES, AES. The sequence involves channel assignment, call announcement, test signal units, and channel release messages between these entities.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg)
+
+```
+
+sequenceDiagram
+    participant Call
+    participant OtherGES as "Other" GES
+    participant NCS
+    participant LogonGES as Log-on GES
+    participant AES
+
+    Note left of Call: Call
+    Call->>OtherGES: Request for channel assignment
+    OtherGES->>NCS: ISL
+    NCS-->>OtherGES: C-channel assign.
+    OtherGES->>LogonGES: Call announcement
+    LogonGES->>AES: Pd
+    LogonGES->>AES: Pd
+    Note right of AES: Test signal units (continuous)
+    OtherGES->>NCS: C-channel assignment
+    NCS-->>LogonGES: Call announcement
+    LogonGES->>AES: C, sub-band
+    Note right of AES: Test signal units (continuous)
+    OtherGES->>NCS: Test signal units (continuous)
+    NCS-->>LogonGES: C, sub-band
+    LogonGES->>AES: C, sub-band
+    Note right of AES: Test signal units (continuous)
+    OtherGES->>NCS: C-channel release
+    NCS-->>OtherGES: ISL
+    OtherGES->>NCS: ISL
+    NCS-->>OtherGES: C-channel release ack.
+  
+```
+
+Sequence diagram showing ground-to-air telephone call set-up sequence via other GES (overflow mode). Lifelines: Call, 'Other' GES, NCS, Log-on GES, AES. The sequence involves channel assignment, call announcement, test signal units, and channel release messages between these entities.
+
+T1128370-90/d13
+
+Further procedure is the same as for air to ground call without NCS till GES monitors for carrier off after clearing
+
+ISL Interstation link  
+Pd See 1.3.2
+
+FIGURE I.10/Q.1151  
+**Ground-to-air telephone call set-up sequence via other GES (overflow mode)**
+
+![Sequence diagram showing Ground-to-air telephone call user switchhook signalling between GES and AES. The diagram illustrates the interaction for answer and clearback sequences using C sub-band messages.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg)
+
+```
+
+sequenceDiagram
+    participant GES
+    participant AES
+    Note right of AES: B-Party off-hook
+    AES->>GES: C, sub-band (Answer)
+    Note left of GES: Acknowledge
+    GES->>AES: C, sub-band
+    Note right of AES: B-Party on-hook (Clearback)
+    AES->>GES: C, sub-band (Channel releasea) then carrier off)
+    Note left of GES: Channel releasea)  
+GES monitors for carrier off
+    GES->>AES: C, sub-band
+    Note right of AES: Carrier off
+    Note left of GES: B: Clearback sequence  
+(A-Party) On-hook
+    GES->>AES: C, sub-band (Channel releasea))
+    Note right of AES: Channel releasea)
+    GES->>AES: C, sub-band
+    Note right of AES: Carrier off
+  
+```
+
+GES Monitors for carrier off  
+C: Clearing sequence
+
+T1128380-90/d14
+
+Sequence diagram showing Ground-to-air telephone call user switchhook signalling between GES and AES. The diagram illustrates the interaction for answer and clearback sequences using C sub-band messages.
+
+<sup>a)</sup> Repeated 6 times.
+
+FIGURE I.11/Q.1151  
+**Ground-to-air telephone call user switchhook signalling**
+
+#### I.6.4 Supervisory signalling
+
+**I.6.4.1** After call set-up, all subsequent supervisory functions are normally performed by means of subband signalling on the C-channel.
+
+**I.6.4.2** Continuity checking of the satellite voice channel is done by means of test packets transmitted on the sub-band of the C-channel.
+
+**I.6.4.3** Sub-band signalling on the C-channel is also used for answer/clearing signals, and to provide additional signalling capacity for potential future use in interworking with the terrestrial ISDNs.
+
+**I.6.4.4** Terrestrial network audible tones (ringing, busy, congestion, etc.) are passed to the AES in-band over the voice channel for air-to-ground calls. In the case of ground-to-air calls, the MSSC should return call progress and call failure causes to the terrestrial network by means of appropriate signals, from the signalling system in use. When required (due to the inadequacy of the signalling system in use), the MSSC should also generate audible tones back into the terrestrial network to the calling party.

marked/Q/T-REC-Q.1210-199510-I_PDF-E/raw.md

@@ -0,0 +1,402 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**Q.1210**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(10/95)
+
+**INTELLIGENT NETWORK**
+
+---
+
+**Q.1210-SERIES INTELLIGENT NETWORK  
+RECOMMENDATION STRUCTURE**
+
+**ITU-T Recommendation Q.1210**
+
+(Previously "CCITT Recommendation")
+
+---
+
+# FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation Q.1210 was prepared by ITU-T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 17th of October 1995.
+
+---
+
+## NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **SUMMARY**
+
+A block of one hundred numbers has been set aside in the Q-Series (Q.1200-Q.1299) for the development of Intelligent Network (IN) Recommendations. Q.1210 is a new Recommendation in the IN-Series that was developed in conjunction with the IN CS-1 refinements to better align the IN CS-1 Recommendations with the overall IN CS-n Recommendation structure.
+
+This Recommendation, the first in the IN Capability Set-1 Series, has been developed to show the organization of the IN CS-1 Recommendations in a meaningful way and to assist users in locating topics of interest. It provides a structural overview of the Q.1200-Series, IN Recommendations, as well as the content of each of the Q.1210-Series, IN CS-1 Recommendations.
+
+Associated standards work is contained in the Q.1200-Series as well as the Q.1210-Series of IN Recommendations.
+
+
+
+# Q.1210-SERIES INTELLIGENT NETWORK RECOMMENDATION STRUCTURE
+
+(Geneva, 1995)
+
+## General Q.1200-Series structure
+
+Table 1 shows the overall Q.1200-Series Intelligent Network Recommendation structural distribution through the tens digits (1200, 1210, 1220, etc.) and the ones digits (i.e. 1201, 1202, 1203, etc.).
+
+TABLE 1/Q.1210
+
+### Recommendation framework structure
+
+|               |                                                                                     |
+|---------------|-------------------------------------------------------------------------------------|
+| 00 – General  |                                                                                     |
+| 10 – CS-1     | 1 – Principles introduction                                                         |
+| 20 – CS-2     | 2 – Service Plane (not included for CS-1)                                           |
+| 30 – CS-3     | 3 – Global Functional Plane                                                         |
+| 40 – CS-4     | 4 – Distributed Functional Plane                                                    |
+| 50 – CS-5     | 5 – Physical Plane                                                                  |
+| 60 – CS-6     | 6 – For future use                                                                  |
+| 70 – CS-7     | 7 – For future use                                                                  |
+| 80 – CS-8     | 8 – Interface Recommendations                                                       |
+| 90 – Glossary | 9 – Intelligent Network user's guide                                                |
+| NOTES         |                                                                                     |
+| 1             | Recommendation Q.1200 is assigned as for the IN Recommendation framework structure. |
+| 2             | Q.1290-Series has been set aside for the glossary.                                  |
+
+# **Q.1210-SERIES INTELLIGENT NETWORK RECOMMENDATION STRUCTURE**
+
+## **1 Q.1210-Series Intelligent Network Recommendation overview**
+
+### **Q.1210 – Q-Series Intelligent Network Recommendation structure**
+
+- 1 Q.1210-Series Intelligent Network Recommendation overview
+
+### **Q.1211 – Introduction to Intelligent Network capability set-1**
+
+- 1 Introduction
+- 2 Phased standardization
+- 3 General description and scope of CS-1
+  - 3.1 Criteria for CS-1
+  - 3.2 Evolution of CS-1
+- 4 Overview of CS-1 Recommendations
+- 5 Service aspects
+  - 5.1 Type A and B services
+  - 5.2 Target set of CS-1 service and service features
+  - 5.3 Network support of CS-1 services
+- 6 Network aspects
+  - 6.1 Network functions
+  - 6.2 Control architecture principles
+  - 6.3 Feature interactions
+  - 6.4 Consistency among CS-1 supported service features
+- 7 Functional relationships and interfaces
+  - 7.1 Reference points and identifiers for functional relationships
+  - 7.2 Control classes
+  - 7.3 Reference point identifiers of functional interfaces
+  - 7.4 CS-1 Non-IN connection and call control
+  - 7.5 CS-1 IN service control
+  - 7.6 Service management for CS-1
+  - 7.7 Network interworking in CS-1
+  - 7.8 Summary of CS-1 functional interfaces
+
+Annex A – Examples of relationships and mappings between services and service features
+
+Annex B – Short prose descriptions of targeted services and service features
+
+### **Q.1213 – Global functional plane for Intelligent Network CS-1**
+
+- 1 General
+- 2 Scope of IN global functional plane for capability set 1
+- 3 References
+- 4 IN CS-1 global functional plane
+  - 4.1 Role of SIBs in the global functional plane
+  - 4.2 Additional characteristics of a IN CS-1 SIBs
+  - 4.3 CS-1 global functional plane model
+  - 4.4 Terminology
+- 5 IN CS-1 Service Independent Building Blocks (SIBs)
+  - 5.1 Data parameters for SIBs
+  - 5.2 Method to describe SIBs
+
+- 5.3 ALGORITHM
+- 5.4 AUTHENTICATE
+- 5.5 CHARGE
+- 5.6 COMPARE
+- 5.7 DISTRIBUTION
+- 5.8 LIMIT
+- 5.9 LOG CALL INFORMATION
+- 5.10 QUEUE
+- 5.11 SCREEN
+- 5.12 SERVICE DATA MANAGEMENT
+- 5.13 STATUS NOTIFICATION
+- 5.14 TRANSLATE
+- 5.15 USER INTERACTION
+- 5.16 VERIFY
+- 6 Basic call process
+  - 6.1 General
+  - 6.2 Point of initiation and point of return
+  - 6.3 BCP stage 1 description
+- 7 Global service logic
+  - 7.1 Relationship between GSL and BCP
+  - 7.2 Relationship between global service logic and SIBs
+- 8 Mapping of the service plane to the global functional plane
+
+### **Q.1214 – Distributed functional plane for Intelligent Network CS-1**
+
+- 1 General
+- 2 Scope of IN distributed functional plane for capability set 1
+  - 2.1 End-user access
+  - 2.2 Service invocation and control
+  - 2.3 End-user interaction
+  - 2.4 Service management
+- 3 Distributed functional plane model for CS-1
+  - 3.1 Explanation of diagram
+  - 3.2 IN functional model
+  - 3.3 Definition of Functional Entities related to IN service execution
+- 4 Functional entity call/service processing models
+  - 4.1 Overview
+  - 4.2 SSF/CCF model
+    - 4.2.1 General
+    - 4.2.2 Basic Call Manager (BCM)
+    - 4.2.3 IN-Switching Manager (IN-SM)
+    - 4.2.4 Feature Interaction Manager (FIM)/Call Manager (CM)
+    - 4.2.5 Relationship of SSF/CCF model components
+    - 4.2.6 Relationship of SSF/CCF to SCF
+  - 4.3 Specialized Resource Function (SRF) model
+    - 4.3.1 General
+    - 4.3.2 SRF components
+    - 4.3.3 SRF and other entity relationships
+    - 4.3.4 Objects of SRF management
+  - 4.4 Service Control Function (SCF) model
+    - 4.4.1 General
+    - 4.4.2 SCF components
+    - 4.4.3 Functional routine categories
+
+- 4.5 Service Data Function (SDF) model
+  - 4.5.1 General
+  - 4.5.2 SDF components
+  - 4.5.3 Data types handled by the SDF
+- 5 Stage 2 description of Service Independent Building Blocks (SIBs)
+  - 5.1 Introduction
+    - 5.1.1 Functional model
+    - 5.1.2 Description of functional entities
+    - 5.1.3 Numbering of functional entity actions
+    - 5.1.4 Relationship with clause 6 (Information flow descriptions)
+    - 5.1.5 Organization of clause 5
+    - 5.1.6 Abbreviations used in clause 5
+  - 5.2 SIB stage 2 descriptions
+    - 5.2.1 ALGORITHM SIB
+    - 5.2.2 CHARGE SIB
+    - 5.2.3 COMPARE SIB
+    - 5.2.4 DISTRIBUTION SIB
+    - 5.2.5 LIMIT SIB
+    - 5.2.6 LOG CALL INFORMATION SIB
+    - 5.2.7 QUEUE SIB
+    - 5.2.8 SCREEN SIB
+    - 5.2.9 SERVICE DATA MANAGEMENT SIB
+    - 5.2.10 STATUS NOTIFICATION SIB
+    - 5.2.11 TRANSLATE SIB
+    - 5.2.12 USER INTERACTION SIB
+    - 5.2.13 VERIFY SIB
+    - 5.2.14 AUTHENTICATE SIB
+  - 5.3 BASIC CALL PROCESS SIB
+    - 5.3.1 Description
+    - 5.3.2 Information flows
+    - 5.3.3 SDLs
+    - 5.3.4 Functional entity actions
+  - 5.4 Stage 2 description of other distributed functionality
+    - 5.4.1 Activity test functionality
+    - 5.4.2 Call Gap capability
+  - 5.5 Mapping of the global functional plane to the distributed functional plane
+    - 5.5.1 Mapping of POIs and PORs to DPs and PICs
+    - 5.5.2 Relating the GFP to the DFP
+- 6 Relationships between FEs
+  - 6.1 General
+  - 6.2 Relationships
+  - 6.3 Information flows between FEs
+  - 6.4 SCF-SSF relationship
+    - 6.4.1 General
+    - 6.4.2 Information flows between SCF and SSF
+    - 6.4.3 Call party handling information flows
+    - 6.4.4 IE rules for SSF/CCF to SCF information flows
+  - 6.5 SCF-SRF relationship
+    - 6.5.1 General
+    - 6.5.2 Information flows between the SCF and SRF
+  - 6.6 SCF-SDF relationship
+    - 6.6.1 General
+    - 6.6.2 Information flows between the SCF and SDF
+  - 6.7 Summary of information flows and related SIBs
+
+Annex A – Communication between call segments
+
+Annex B – BCSM SDL Diagrams
+
+Appendix I – Aspects of the distributed functional plane identified as “for further study” (FFS) relative to CS-1
+
+Appendix II – Charging scenarios examples
+
+### **Q.1215 – Physical plane for Intelligent Network CS-1**
+
+- 1 General
+- 2 Requirements and assumptions
+  - 2.1 Requirements
+  - 2.2 Assumptions
+- 3 Physical Entities (PEs)
+- 4 Mapping requirements
+- 5 Mapping the distributed functional plane to the physical plane
+  - 5.1 Mapping of functional entities to physical entities
+  - 5.2 Mapping FE-FE relationships to PE-PE relationships
+  - 5.3 Selection of underlying protocol platforms
+    - 5.3.1 SCP-SSP interface
+    - 5.3.2 AD-SSP interface
+    - 5.3.3 IP-SSP interface
+    - 5.3.4 SN-SSP interface
+    - 5.3.5 SCP-IP interface
+    - 5.3.6 AD-IP interface
+    - 5.3.7 SCP-SDP interface
+    - 5.3.8 User interfaces
+
+### **Q.1218 – Interface Recommendations for Intelligent Network CS-1**
+
+- 0 Introduction
+  - 0.1 Normative references
+  - 0.2 Definition methodology
+  - 0.3 Example physical scenarios
+  - 0.4 INAP protocol architecture
+  - 0.5 INAP addressing
+  - 0.6 Relationship between Recommendation Q.1214 and this Recommendation
+  - 0.7 Compatibility mechanisms used for INAP
+- 1 SACF/MACF rules
+  - 1.1 Reflection of TCAP AC
+  - 1.2 Sequential/Parallel execution of operations
+- 2 ASN.1 introduction
+  - 2.1 SSF/SCF, SCF/SRF, SSF/SRF interfaces
+    - 2.1.1 Operation types IN CS-1 operations
+    - 2.1.2 Error types IN CS-1 error
+    - 2.1.3 Data types IN CS-1 data types
+    - 2.1.4 Operation and error codes IN CS-1 codes
+    - 2.1.5 Application context
+  - 2.2 SCF/SDF Interface
+    - 2.2.1 Introduction to IN X.500 DAP subset
+    - 2.2.2 The IN X.500 DAP subset
+      - 2.2.2.1 Review of X.511 for use in the IN
+      - 2.2.2.2 Directory Access Protocol Subset
+      - 2.2.2.3 X.501 profile
+
+- 2.2.2.4 Enhancements to X.500 for the support of the IN CS-1
+- 2.2.2.5 ASN.1 Profile of the Directory Abstract Service for the IN CS-1
+
+## 3 Semantics
+
+- 3.1 Definition of procedures and entities
+  - 3.1.1 SSF Application Entity procedures
+  - 3.1.2 SCF Application Entity procedures
+  - 3.1.3 SRF Application Entity procedures
+  - 3.1.4 SDF Application Entity procedures
+- 3.2 Error procedures
+- 3.3 Detailed Operation procedures
+- 3.4 Services assumed from TCAP
+
+Annex A – INAP SDL diagrams
+
+Annex B – SCSM/SDSM SDLs
+
+Appendix I – Aspects of the Intelligent Network interface identified as “for further study” (FFS) relative to CS-1
+
+Appendix II – Expanded ASN.1 Coding
+
+### **Q.1219 – Intelligent Network users guide for capability set-1**
+
+## 1 Scope
+
+- 1.1 Target audience
+- 1.2 Intended use
+- 1.3 Framework outline of Q.1200-Series
+- 1.4 Initial set of capabilities
+- 1.5 State of Maturity of the CS-1 Recommendations
+- 1.6 Service Decomposition for CS-1
+
+## 2 Intelligent Network objectives
+
+## 3 Capabilities provided by Capability Set-1
+
+- 3.1 Service implementation independence
+- 3.2 Multi-Vendor capability
+- 3.3 Multi-Network capability
+- 3.4 Rapid service delivery
+- 3.5 Service deployment
+
+## 4 Service aspects for CS-1
+
+- 4.1 Basic Service Capabilities
+- 4.2 Type A service category
+- 4.3 Type B service category
+- 4.4 Phases of deployed services
+
+## 5 CS-1 Architecture
+
+- 5.1 Functions
+- 5.2 IN CS-1 plane relationships
+  - 5.2.1 IN CS-1 Service Plane
+  - 5.2.2 IN CS-1 Global Functional
+  - 5.2.3 IN CS-1 Distributed Functional Plane
+  - 5.2.4 IN CS-1 Physical Plane
+- 5.3 Interfaces and relationships
+
+## 6 Infrastructure in CS-1
+
+- 6.1 Service Independent Building Blocks (SIBs)
+- 6.2 Service logic
+
+- 6.3 Functional Entity Call/Service Logic Processing Models
+    - 6.3.1 Call Modelling for IN CS-1
+    - 6.3.2 Modelling of Service Logic Processing for IN CS-1
+    - 6.3.3 General considerations
+  - 6.4 Information flows
+    - 6.4.1 Requirement for an information flow from SCF to SSF to Initiate “Call Follow-On”
+  - 6.5 Intelligent Network Applications Protocol (INAP)
+    - 6.5.1 General ASE discussion
+    - 6.5.2 General Application Context discussion
+    - 6.5.3 Service Filtering
+    - 6.5.4 Optional Parameters
+    - 6.5.5 Considerations for the use and understanding of various operations and procedures in Recommendation Q.1218
+  - 6.6 Requirement on Inter-Exchange and User-Network Signalling
+    - 6.6.1 General
+    - 6.6.2 Interworking INAP and Network or Access Signalling
+    - 6.6.3 Terminal Type and Access Type of User
+    - 6.6.4 Optional Parameters in DP operations
+    - 6.6.5 Miscellaneous
+  - 7 Service example
+    - 7.1 Utilizing CS-1 capabilities
+    - 7.2 Guidelines for service scenarios
+    - 7.3 Format for service scenarios
+  - 8 Physical deployment scenarios
+    - 8.1 Mapping FEs to PEs
+    - 8.2 Mapping of FE-FE relationships to PE-PE relationships
+  - 9 Future IN Capability Sets
+    - 9.1 Generic plans
+    - 9.2 “Stretch forward/ease back”
+    - 9.3 Evolvable capabilities
+    - 9.4 Evolvability concepts
+- Annex A – IN CS-1 Service Scenario Examples
+- Annex B – BCSM SDLs

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+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**Q.1220**
+
+(09/97)
+
+SERIES Q: SWITCHING AND SIGNALLING
+
+Intelligent Network
+
+---
+
+**Q.1220-series Intelligent Network  
+Capability Set 2 Recommendation structure**
+
+ITU-T Recommendation Q.1220
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T Q-SERIES RECOMMENDATIONS
+
+## **SWITCHING AND SIGNALLING**
+
+|                                                          |                      |
+|----------------------------------------------------------|----------------------|
+| SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE           | Q.1–Q.3              |
+| INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING       | Q.4–Q.59             |
+| FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN | Q.60–Q.99            |
+| CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS             | Q.100–Q.119          |
+| SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5     | Q.120–Q.249          |
+| SPECIFICATIONS OF SIGNALLING SYSTEM No. 6                | Q.250–Q.309          |
+| SPECIFICATIONS OF SIGNALLING SYSTEM R1                   | Q.310–Q.399          |
+| SPECIFICATIONS OF SIGNALLING SYSTEM R2                   | Q.400–Q.499          |
+| DIGITAL EXCHANGES                                        | Q.500–Q.599          |
+| INTERWORKING OF SIGNALLING SYSTEMS                       | Q.600–Q.699          |
+| SPECIFICATIONS OF SIGNALLING SYSTEM No. 7                | Q.700–Q.849          |
+| DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1               | Q.850–Q.999          |
+| PUBLIC LAND MOBILE NETWORK                               | Q.1000–Q.1099        |
+| INTERWORKING WITH SATELLITE MOBILE SYSTEMS               | Q.1100–Q.1199        |
+| <b>INTELLIGENT NETWORK</b>                               | <b>Q.1200–Q.1999</b> |
+| BROADBAND ISDN                                           | Q.2000–Q.2999        |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+# **ITU-T RECOMMENDATION Q.1220**
+
+## **Q.1220-SERIES INTELLIGENT NETWORK CAPABILITY SET 2 RECOMMENDATION STRUCTURE**
+
+## **Summary**
+
+This Recommendation explains the structure of the Q.122x (CS-2)-series IN Recommendations and provides their outlines.
+
+### **Source**
+
+ITU-T Recommendation Q.1220 was prepared by ITU-T Study Group 11 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 12th of September 1997.
+
+## FOREWORD
+
+ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 1999
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU.
+
+## CONTENTS
+
+|                                                                    | <i>Page</i> |
+|--------------------------------------------------------------------|-------------|
+| 0 Introduction .....                                               | 1           |
+| 1 General Q.1200-series structure .....                            | 1           |
+| 2 Q.122x-series Intelligent Network Recommendations overview ..... | 1           |
+
+
+
+## Q.1220-SERIES INTELLIGENT NETWORK CAPABILITY SET 2 RECOMMENDATION STRUCTURE
+
+*(Geneva, 1997)*
+
+# 0 Introduction
+
+A block of one hundred numbers has been set aside in the Q series (Q.1200-Q.1299) for the development of Intelligent Network (IN) Recommendations. This Recommendation has been developed to organize the IN CS-2 Recommendations in a meaningful way in order to assist users in locating topics of interest. It provides a structural overview of the content of the Q.1220 series.
+
+Terms and definitions pertinent to IN CS-2 are included in Recommendation Q.1290.
+
+## 1 General Q.1200-series structure
+
+Table 1 shows the overall Q.1200-series Intelligent Network Recommendation naming structure.
+
+**Table 1/Q.1220 – Recommendation framework structure**
+
+|                                                                                                                                       |                                             |
+|---------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------|
+| 1200 – General                                                                                                                        |                                             |
+| 1210 – CS-1                                                                                                                           | 121 – Principles introduction               |
+| 1220 – CS-2                                                                                                                           | 122 – Service plane (not included for CS-1) |
+| 1230 – CS-3                                                                                                                           | 123 – Global functional plane               |
+| 1240 – CS-4                                                                                                                           | 124 – Distributed functional plane          |
+| 1250 – CS-5                                                                                                                           | 125 – Physical plane                        |
+| 1260 – CS-6                                                                                                                           | 126 – For future use                        |
+| 1270 – CS-7                                                                                                                           | 127 – For future use                        |
+| 1280 – CS-8                                                                                                                           | 128 – Interface Recommendation              |
+| 1290 – Glossary                                                                                                                       | 129 – Intelligent network user's guide      |
+| NOTE 1 – 1200 is assigned for the IN Recommendation framework structure.<br>NOTE 2 – 1290-series has been set aside for the glossary. |                                             |
+
+## 2 Q.122x-series Intelligent Network Recommendations overview
+
+### **Q.1220-Q.1220-series Intelligent Network Capability Set 2 Recommendation structure**
+
+- 0 Introduction
+- 1 General Q.1200-series structure
+- 2 Q.122x-series Intelligent Network Recommendations overview
+
+### **Q.1221 – Introduction to Intelligent Network Capability Set 2**
+
+- 1 Introduction
+- 2 Phased standardization
+- 3 General description and scope of IN CS-2
+  - 3.1 Criteria for IN CS-2
+  - 3.2 Evolution of IN CS-2
+- 4 Overview of IN CS-2 Recommendations
+- 5 Service aspects
+  - 5.1 Telecommunication services
+  - 5.2 Service management services
+  - 5.3 Service creation services
+  - 5.4 Network support of IN CS-2 services
+- 6 Network aspects
+  - 6.1 Network functions
+  - 6.2 Control architecture principles
+    - 6.2.1 Service invocation and control
+    - 6.2.2 End-user interactions
+    - 6.2.3 Service management
+  - 6.3 Feature interactions
+  - 6.4 Consistency among IN CS-2 supported service features
+- 7 Functional relationships and interfaces
+  - 7.1 Functional relationships and control classes
+    - 7.1.1 Bearer connection control
+    - 7.1.2 Non-IN call control
+    - 7.1.3 IN service control
+    - 7.1.4 Service management control
+    - 7.1.5 Non-IN call unrelated control
+  - 7.2 Key functions and interfaces
+    - 7.2.1 Single point/multiple points of control
+    - 7.2.2 Single-ended/multi-ended calls
+    - 7.2.3 Mid-call interruption
+    - 7.2.4 Call party handling
+    - 7.2.5 Enhanced SRF
+    - 7.2.6 Call unrelated user interaction
+    - 7.2.7 Out-channel call related user interaction
+    - 7.2.8 Service/feature interaction (service processing)
+    - 7.2.9 Internetworking
+    - 7.2.10 Security
+    - 7.2.11 IN-TMN
+    - 7.2.12 Service management
+    - 7.2.13 Service creation
+    - 7.2.14 Personal mobility
+
+## **Appendix I – IN CS-2 benchmark services and features**
+
+- I.1 General
+- I.2 Definitions
+  - I.2.1 Telecommunication services
+  - I.2.2 Service management services
+  - I.2.3 Service creation services
+- I.3 Telecommunication services
+  - I.3.1 General
+  - I.3.2 Definitions
+  - I.3.3 Mobility service features (UPT, FPLMTS)
+  - I.3.4 Other services
+  - I.3.5 Other service features
+
+- I.4 Service management services
+  - I.4.1 General
+  - I.4.2 Definition
+  - I.4.3 Service management service/service feature
+- I.5 Service creation services
+  - I.5.1 General
+  - I.5.2 Service specification services
+  - I.5.3 Service development services
+  - I.5.4 Service verification services
+  - I.5.5 Service deployment services
+  - I.5.6 Service creation service management services
+
+### **Q.1222 – Service plane for Intelligent Network Capability Set 2**
+
+- 1 General
+- 2 Service plane architecture
+  - 2.1 General
+  - 2.2 Characterization of services and service capability requirement
+    - 2.2.1 Service and service feature requirements
+  - 2.3 Service and service feature interaction
+    - 2.3.1 Types of features considered for interactions
+    - 2.3.2 Mechanisms for handling feature interactions
+  - 2.4 Service plane modelling
+
+### **Q.1223 – Global functional plane for Intelligent Network Capability Set 2**
+
+- 1 General
+- 2 Scope of IN global functional plane for capability set 2
+- 3 References
+- 4 Global functional plane modelling for capability set 2
+  - 4.1 Elements on the global functional plane
+    - 4.1.1 Modelling requirements
+    - 4.1.2 Modelling elements
+  - 4.2 The basic call process
+  - 4.3 The capability view
+    - 4.3.1 Definition
+    - 4.3.2 Service independent building blocks
+    - 4.3.3 Methods to describe SIBs
+  - 4.4 Interaction management
+    - 4.4.1 Interaction between SIBs
+    - 4.4.2 Interaction handling methods in the SIB definition phase
+  - 4.5 The service view
+    - 4.5.1 Definition
+    - 4.5.2 Global service logic
+    - 4.5.3 SIB operations
+    - 4.5.4 Characteristics of an HLSIB
+    - 4.5.5 Characteristics of a service process
+    - 4.5.6 Communication between service processes
+    - 4.5.7 Domains
+  - 4.6 Terminology
+- 5 IN CS-2 Service Independent Building Blocks (SIBs)
+  - 5.1 ALGORITHM
+  - 5.2 AUTHENTICATE
+  - 5.3 CHARGE
+  - 5.4 COMPARE
+  - 5.5 DISTRIBUTION
+  - 5.6 END
+  - 5.7 INITIATE SERVICE PROCESS
+  - 5.8 JOIN
+
+- 5.9 LOG CALL INFORMATION
+  - 5.10 MESSAGE HANDLER
+  - 5.11 QUEUE
+  - 5.12 SCREEN
+  - 5.13 SERVICE DATA MANAGEMENT
+  - 5.14 SERVICE FILTER
+  - 5.15 SPLIT
+  - 5.16 STATUS NOTIFICATION
+  - 5.17 TRANSLATE
+  - 5.18 USER INTERACTION
+  - 5.19 VERIFY
+  - 6 IN CS-2 specialized SIBs
+    - 6.1 The basic call process
+      - 6.1.1 General
+      - 6.1.2 Points of initiation and points of return
+      - 6.1.3 BCP stage 1 description
+    - 6.2 Basic call unrelated process
+      - 6.2.1 General
+      - 6.2.2 Points of initiation and points of return
+      - 6.2.3 BCUP stage 1 description
+  - 7 Mapping of the service plane to the global functional plane
+- Annex A – Overview of the SIBs and SIB operations
+- Appendix I – IN management
+- I.1 Management view
+  - I.2 The Basic Service Management Process (BSMP)
+    - I.2.1 The basic service management process
+
+### **Q.1224 – Distributed functional plane for Intelligent Network Capability Set 2**
+
+- 1 General
+  - 1.1 Normative references
+  - 1.2 Abbreviations and acronyms
+- 2 Scope of IN distributed functional plane for capability set 2
+  - 2.1 End user access
+  - 2.2 Service invocation and control
+  - 2.3 End user interaction
+  - 2.4 IN service management functionality
+  - 2.5 Call Party Handling
+    - 2.5.1 Overview
+    - 2.5.2 Background and motivation
+    - 2.5.3 Scope
+    - 2.5.4 Assumptions
+    - 2.5.5 Core Capabilities
+  - 2.6 Internetworking
+  - 2.7 Security
+  - 2.8 Out-Channel Call Related User Interaction (OCCRUI)
+  - 2.9 Out-Channel Call Unrelated User Interaction (OCUUI)
+  - 2.10 Wireless access
+  - 2.11 Feature interactions
+
+- 3 Distributed functional model for IN CS-2
+  - 3.1 Explanation of diagram
+  - 3.2 IN functional model
+  - 3.3 Definition of functional entities related to IN service execution
+    - 3.3.1 CCA function (CCAF)
+    - 3.3.2 CC function (CCF)
+    - 3.3.3 SS function (SSF)
+    - 3.3.4 SC function (SCF)
+    - 3.3.5 SD function (SDF)
+    - 3.3.6 SR function (SRF)
+    - 3.3.7 IA function (IAF)
+    - 3.3.8 CUS function (CUSF)
+    - 3.3.9 SCUA function (SCUAF)
+    - 3.3.10 SM function (SMF)
+  - 3.4 Use of individual relationships between functional entities related to IN service execution
+    - 3.4.1 SCF-SSF relationship
+    - 3.4.2 SCF-SCF relationship
+    - 3.4.3 SCF-IAF relationship
+    - 3.4.4 SRF-CCF relationship
+    - 3.4.5 SCF-SRF relationship
+    - 3.4.6 SRF-SCF relationship
+    - 3.4.7 SRF-SMF relationship
+    - 3.4.8 SDF-SDF relationship
+    - 3.4.9 SCF-SDF relationship
+    - 3.4.10 SCF-CUSF relationship
+    - 3.4.11 CUSF-SSF relationship
+    - 3.4.12 CUSF-CCF relationship
+    - 3.4.13 SMF-SCF relationship
+    - 3.4.14 SMF-SDF relationship
+    - 3.4.15 SMF-SSF/CCF relationship
+    - 3.4.16 SMF-SRF relationship
+    - 3.4.17 SMF-SMAF relationship
+    - 3.4.18 SMF-SCEF relationship
+    - 3.4.19 SMF-SMF relationship
+    - 3.4.20 SMF-CUSF relationship
+  - 3.5 Overview of functional entity call/service logic processing models
+- 4 SSF/CCF model
+  - 4.1 General
+  - 4.2 Basic Call Manager (BCM)
+    - 4.2.1 BCSM
+    - 4.2.2 CS-2 BCSM description
+    - 4.2.3 BCSM resume points and BCSM transitions in the IN CS-2 call model
+    - 4.2.4 BCSM indications for the CS-2 call model
+    - 4.2.5 BCSM detection points
+    - 4.2.6 DP criteria
+    - 4.2.7 Trigger types and trigger precedence
+    - 4.2.8 DP processing
+    - 4.2.9 Out-Channel Call Related User Interaction (OCCRUI)
+  - 4.3 IN-Switching Manager (IN-SM)
+    - 4.3.1 IN-Switching State Model (IN-SSM)
+    - 4.3.2 IN-SM Core Capabilities for Call Party Handling
+    - 4.3.3 The Connection View State (CVS) approach
+    - 4.3.4 The Hybrid Approach
+    - 4.3.5 IN-SSM EDPs
+    - 4.3.6 SSF resource control
+
+- 4.4 Feature Interactions Manager (FIM)/Call Manager (CM)
+  - 4.4.1 FIM/CM functions
+  - 4.4.2 Service logic instance interactions considerations
+  - 4.4.3 FIM mechanisms
+- 4.5 Relationship of SSF/CCF Model Components
+  - 4.5.1 General
+  - 4.5.2 Typical sequence of model actions
+- 4.6 Relationship of SSF/CCF to SCF
+- 5 Specialized Resource Function (SRF) model
+  - 5.1 General
+  - 5.2 SRF Components
+    - 5.2.1 Functional Entity Access Manager (FEAM)
+    - 5.2.2 Resource Control Part (RCP)
+    - 5.2.3 Resource Function Part (RFP)
+    - 5.2.4 Data Part (DP)
+  - 5.3 Objects of SRF management
+- 6 Service Control Function (SCF) model
+  - 6.1 General
+  - 6.2 SCF components
+    - 6.2.1 General
+    - 6.2.2 Service Logic Execution Manager (SLEM)
+    - 6.2.3 SCF data access manager
+    - 6.2.4 Functional routine manager
+    - 6.2.5 Functional Entity Access Manager (FEAM)
+    - 6.2.6 SLP manager
+    - 6.2.7 Security manager
+  - 6.3 Functional routine categories
+    - 6.3.1 SLPI management functional routines
+    - 6.3.2 SLPI communication functional routines
+    - 6.3.3 Timer management functional routines
+    - 6.3.4 Data management interface functional routines
+    - 6.3.5 Asynchronous event handling functional routines
+    - 6.3.6 Connection management functional routines
+    - 6.3.7 Specialized resource management functional routines
+    - 6.3.8 OAM functional routines
+- 7 Service Data Function (SDF) model
+  - 7.1 General
+  - 7.2 SDF components
+    - 7.2.1 General
+    - 7.2.2 SDF data manager
+    - 7.2.3 Functional entity access manager
+    - 7.2.4 Security manager
+  - 7.3 Data types handled by SDF
+- 8 Call Unrelated Service Function (CUSF) model
+  - 8.1 General
+  - 8.2 Basic Non-Call Manager (BNCM)
+    - 8.2.1 BCUSM
+    - 8.2.2 BCUSM description for CS-2
+    - 8.2.3 Transition for BCUSM
+    - 8.2.4 BCUSM DP criteria
+  - 8.3 Description of relationship model
+
+- 9 Service Management Function (SMF) model
+  - 9.1 General
+  - 9.2 SMF components
+    - 9.2.1 General
+- 10 Mapping of the global functional plane to the distributed functional plane
+  - 10.1 Mapping of POIs and PORs to DPs and PICs
+- 11 Information flow diagrams and distributed service logic in the DFP
+  - 11.1 Introduction
+    - 11.1.1 Functional model
+    - 11.1.2 Description of functional entities
+    - 11.1.3 Numbering of functional entity actions
+    - 11.1.4 Relationship with clause 12 (information flow descriptions)
+    - 11.1.5 Organization of clause 11
+    - 11.1.6 Generic security information flows
+    - 11.1.7 SDF-SDF interactions
+    - 11.1.8 SCF-SCF interactions
+  - 11.2 SIB stage 2 descriptions
+    - 11.2.1 ALGORITHM SIB
+    - 11.2.2 AUTHENTICATE SIB
+    - 11.2.3 CHARGE SIB
+    - 11.2.4 COMPARE SIB
+    - 11.2.5 DISTRIBUTION SIB
+    - 11.2.6 END SIB
+    - 11.2.7 INITIATE SERVICE PROCESS SIB
+    - 11.2.8 JOIN SIB
+    - 11.2.9 LOG CALL INFORMATION SIB
+    - 11.2.10 MESSAGE HANDLER SIB
+    - 11.2.11 QUEUE SIB
+    - 11.2.12 SCREEN SIB
+    - 11.2.13 SERVICE DATA MANAGEMENT SIB
+    - 11.2.14 SERVICE FILTER SIB
+    - 11.2.15 SPLIT SIB
+    - 11.2.16 STATUS NOTIFICATION SIB
+    - 11.2.17 TRANSLATE SIB
+    - 11.2.18 USER INTERACTION SIB
+    - 11.2.19 VERIFY SIB
+  - 11.3 BASIC PROCESS SIBs
+    - 11.3.1 BASIC CALL PROCESS SIB
+    - 11.3.2 BASIC CALL UNRELATED PROCESS SIB
+  - 11.4 Stage 2 description of other distributed functionality
+    - 11.4.1 Activity test functionality
+    - 11.4.2 Call gap capability
+  - 11.5 Distributed service logic
+    - 11.5.1 SDL diagrams
+    - 11.5.2 Distributed service logic for SSF
+    - 11.5.3 Distributed service logic for assist/hand-off SSF
+    - 11.5.4 Distributed service logic for SRF
+    - 11.5.5 Distributed service logic for SCF
+    - 11.5.6 Distributed service logic for SDF
+    - 11.5.7 Distributed service logic for CUSF
+  - 11.6 Mapping between information flows and SIBs
+- 12 Relationships between FEs
+  - 12.1 General
+  - 12.2 Relationships
+  - 12.3 Information flows between FEs
+
+- 12.4 SCF-SSF relationship
+  - 12.4.1 General
+  - 12.4.2 DP specific Common Elements
+  - 12.4.3 Information flows between SCF and SSF
+  - 12.4.4 IE Definitions for SSF/CCF to SCF information flows
+- 12.5 SCF-SRF relationship
+  - 12.5.1 General
+  - 12.5.2 Information flows between the SCF and SRF
+  - 12.5.3 IE Definitions for SCF to SRF information flows
+- 12.6 SCF-SCF relationship
+  - 12.6.1 General
+  - 12.6.2 Information flows between the SCF and SCF
+  - 12.6.3 IE Definitions for SCF to SCF information flows
+- 12.7 SCF-CUSF relationship
+  - 12.7.1 General
+  - 12.7.2 Information flows between the SCF and CUSF
+  - 12.7.3 IE Description for the SCF-CUSF information flows
+- 12.8 SCF-SDF relationship
+  - 12.8.1 General
+  - 12.8.2 Information flows between the SCF and SDF
+  - 12.8.3 IE Description for the SCF-SDF information flows
+- 12.9 SDF-SDF relationship
+  - 12.9.1 General
+  - 12.9.2 Information flows between the SDF and SDF
+  - 12.9.3 IE Description for the SDF-SDF information flows
+- 12.10 IE Population Rules
+  - 12.10.1 SSF/CCF to SCF Information Flows
+- 12.11 Summary of information flows and related SIBs
+
+## Annex A – Mobility aspects
+
+- A.1 General
+- A.2 Scope
+- A.3 Mobility Aspects of Distributed Functional Model for IN CS-2
+  - A.3.1 Explanation of the diagram
+  - A.3.2 Wireless access enhancements to the IN functional model
+  - A.3.3 Definitions of wireless access specific functional entities related to IN service execution
+  - A.3.4 Use of individual relationships between FEs for wireless access
+- A.4 Example mapping of wireless access FEs to physical platforms
+  - A.4.1 Example mapping 1
+  - A.4.2 Example mapping 2
+  - A.4.3 Example mapping 3
+  - A.4.4 Example mapping 4
+  - A.4.5 Example mapping 5
+  - A.4.6 Example mapping 6
+  - A.4.7 Example mapping 7: RCF and CRACF in RS, CURACF in SCP
+  - A.4.8 Example mapping 8: RCF and CRACF in RS, CURACF in standalone platform
+  - A.4.9 Example mapping 9: RCF in Radio System, CRACF in standalone platform CURACF in SCP
+  - A.4.10 Example mapping 10: RCF in Radio System, CRACF in standalone platform and CURACF in standalone platform
+
+## Annex B – Telecommunications Management Network (TMN) concepts
+
+- B.1 Introduction
+- B.2 The TMN functional architecture
+  - B.2.1 Operations Systems
+  - B.2.2 Work Station Functions
+  - B.2.3 The Human Machine Adaptation (HMA)
+  - B.2.4 TMN information modelling
+- B.3 Applying TMN concepts to the IN
+  - B.3.1 IN management functional model
+  - B.3.2 Correspondence between the IN concept of SIB and the TMN concept of MO
+  - B.3.3 IN management protocols
+- B.4 Modelling aspects imported from TMN
+  - B.4.1 Mappings of IN SMF onto TMN logical layers
+  - B.4.2 Mapping of IN SMF onto TMN management functions
+  - B.4.3 Mapping of the IN SCEF onto TMN logical layers
+- B.5 IN management and generic TMN management
+  - B.5.1 Management process independence
+  - B.5.2 SMF complexity
+- B.6 IN SMF-SMF internetworking relationship mapping to TMN
+  - B.6.1 Fault management example
+
+## Annex C – IN SSF Q3 Management Information Model
+
+- C.1 Introduction
+  - C.1.1 Technical approach
+- C.2 SSF functional decomposition
+  - C.2.1 Rationale
+  - C.2.2 Method
+- C.3 SSF management requirements
+  - C.3.1 Rationale
+  - C.3.2 Method
+- C.4 SSF management information model
+
+## Annex D – IN testing and fault management
+
+- D.1 Introduction
+- D.2 IN testing capabilities for the SSF/CCF
+  - D.2.1 Translation Check
+  - D.2.2 Trigger Data Check
+  - D.2.3 SSF/CCF Query Test
+  - D.2.4 Using the SSF/CCF testing capabilities
+- D.3 IN end-to-end testing
+  - D.3.1 IN end-to-end testing information elements
+  - D.3.2 SSF to SCF
+  - D.3.3 SCF to SSF
+  - D.3.4 SCF-SRF
+  - D.3.5 SRF-SCF
+
+### Appendix I – Example/application of IN SSF Q3 management information model
+
+- I.1 Introduction
+- I.2 SSF functional decomposition
+  - I.2.1 SSF model
+- I.3 Example to illustrate development of information models and managed object requirements
+  - I.3.1 General
+  - I.3.2 Example of trigger management information model and managed object requirements
+  - I.3.3 SMF functionality mapping to information model
+  - I.3.4 SSF/CCF functionality mapping to information model
+  - I.3.5 SSF/CCF information model managed object requirements
+
+### Appendix II – Information flows and call models for terminal mobility
+
+- II.1 General
+- II.2 Functional entity call/service processing models for wireless access
+  - II.2.1 Overview
+  - II.2.2 Terminal Access State Model (TASM)
+  - II.2.3 Basic Non-Call Associate State Model for CURACF (BNCSM)
+  - II.2.4 BCSM
+- II.3 Information flow enhancements for wireless access
+  - II.3.1 General
+  - II.3.2 Relationships
+  - II.3.3 Information flows between FEs
+  - II.3.4 SCF-SSF relationship
+  - II.3.5 SCF-CRACF relationship
+  - II.3.6 SCF-CURACF relationship
+
+### Q.1225 – Physical plane for Intelligent Network Capability Set 2
+
+- 1 General
+- 2 Requirements and assumptions
+  - 2.1 Requirements
+  - 2.2 Assumptions
+- 3 Physical Entities (PEs)
+- 4 Mapping requirements
+- 5 Mapping the distributed functional plane to the physical plane
+  - 5.1 Mapping of functional entities to physical entities
+  - 5.2 Mapping of FE-FE relationships to PE-PE relationships
+  - 5.3 Selection of underlying protocol platforms
+    - 5.3.1 SCP-SSP interface
+    - 5.3.2 AD-SSP interface
+    - 5.3.3 IP-SSP interface
+    - 5.3.4 SN-SSP interface
+    - 5.3.5 SCP-IP interface
+    - 5.3.6 AD-IP interface
+    - 5.3.7 SCP-SDP interface
+    - 5.3.8 User interfaces
+    - 5.3.9 Enhanced ISDN CPE-CUSP interface
+    - 5.3.10 AD-CUSP interface
+
+### Q.1228 – Interface Recommendations for Intelligent Network Capability Set 2
+
+- 1 Introduction
+- 2 General
+  - 2.1 Normative references
+  - 2.2 Abbreviations and acronyms
+  - 2.3 Conventions
+- 3 Interface recommendation for telecommunication services
+  - 3.1 General
+    - 3.1.1 Definition methodology
+    - 3.1.2 Example physical scenarios
+    - 3.1.3 INAP protocol architecture
+    - 3.1.4 INAP addressing
+    - 3.1.5 Relationship between Recommendation Q.1224 and this Recommendation
+    - 3.1.6 Compatibility mechanisms used for INAP
+  - 3.2 SACF/MACF rules
+    - 3.2.1 Reflection of TCAP AC
+    - 3.2.2 Sequential/parallel execution of operations
+
+
+
+- 8.3 The IN X.500 DISP Subset
+  - 8.3.1 Shadowing agreement specification
+  - 8.3.2 DSA Shadow Bind
+  - 8.3.3 IN-DSA Shadow Unbind
+  - 8.3.4 Coordinate Shadow Update
+  - 8.3.5 Update Shadow
+  - 8.3.6 Request Shadow Update
+- 8.4 The IN X.500 DSP Subset
+  - 8.4.1 Information types and common procedures
+  - 8.4.2 DSA Bind
+  - 8.4.3 IN DSA Unbind
+  - 8.4.4 Chained Operations
+  - 8.4.5 Chained Errors
+- 8.5 Protocol overview
+  - 8.5.1 ROS-Objects and contracts
+  - 8.5.2 DSP contract and packages
+  - 8.5.3 DISP contract and packages
+- 8.6 Protocol abstract syntax
+  - 8.6.1 DSP Abstract Syntax
+  - 8.6.2 DISP Abstract Syntax
+  - 8.6.3 Directory System Application Context
+  - 8.6.4 Directory Shadow Application Context
+  - 8.6.5 Versions and the rules for extensibility
+- 8.7 Conformance
+  - 8.7.1 Conformance by SDFs
+  - 8.7.2 Conformance by a shadow supplier
+  - 8.7.3 Conformance by a shadow consumer
+- 8.8 ASN.1 modules for the SDF-SDF interface
+  - 8.8.1 IN-CS2-SDF-SDF-Protocol Module
+- 9 SCF/SCF interface
+  - 9.1 SCF/SCF operations and arguments
+  - 9.2 SCF/SCF contracts, packages and Application Contexts
+    - 9.2.1 Protocol overview
+    - 9.2.2 ASN.1 modules
+- 10 SCF/CUSF interface
+  - 10.1 Operations and arguments
+  - 10.2 SCF/CUSF Contracts, Operation Packages, and Application Contexts
+    - 10.2.1 Protocol overview
+    - 10.2.2 ASN.1 module
+- 11 SSF application entity procedures
+  - 11.1 General
+  - 11.2 Model and interfaces
+  - 11.3 Relations between SSF FSM and the CCF and maintenance functions
+  - 11.4 SSF management finite state model (SSME FSM)
+  - 11.5 SSF switching state model (SSM) FSM
+    - 11.5.1 Finite State Model for Call Segment Association (CSA)
+    - 11.5.2 Finite State Model for Call Segment
+  - 11.6 Assisting SSF FSM
+    - 11.6.1 State aa: Idle
+    - 11.6.2 State ab: Waiting For Instructions
+    - 11.6.3 State ac: Waiting For End Of User Interaction
+
+- 11.7 Handed-off SSF FSM
+  - 11.7.1 State ha: Idle
+  - 11.7.2 State hb: Waiting for Instructions
+  - 11.7.3 State hc: Waiting for End Of User Interaction
+- 11.8 User Service Interaction USI FSM
+- 12 SCF application entity procedures
+  - 12.1 General
+  - 12.2 Model and interfaces
+  - 12.3 Relationship between the SCF FSM and the SLPs/maintenance functions
+  - 12.4 Partial SCF Management Entity (SCME) State Transition Diagram
+    - 12.4.1 State M1: Status report idle
+    - 12.4.2 State M2: Waiting for SSF Resource Status Report
+    - 12.4.3 State M3: Service filtering idle
+    - 12.4.4 State M4: Waiting for SSF service filtering response
+    - 12.4.5 State M5: Activity test idle
+    - 12.4.6 State M6: Waiting for activity test response
+    - 12.4.7 State M7: ManageTriggerData idle
+    - 12.4.8 State M8: Waiting for ManageTriggerData activity test response
+    - 12.4.9 The Resource Control Object
+  - 12.5 The SCF Call State Model (SCSM)
+    - 12.5.1 SSF/SRF-related states (SCSM-SSF/SRF)
+    - 12.5.2 SDF-related states (SCSM-SDF)
+    - 12.5.3 SCF-related states
+    - 12.5.4 CUSF-related states (SCSM-CUSF)
+    - 12.5.5 USI\_SCF FSM
+- 13 SRF application entity procedures
+  - 13.1 General
+  - 13.2 Model and interfaces
+  - 13.3 Relationship between the SRF FSM and maintenance functions/bearer connection handling
+  - 13.4 The SRSM
+    - 13.4.1 State 1: Idle
+    - 13.4.2 State 2: Connected
+    - 13.4.3 State 3: User interaction
+  - 13.5 Example SRF control procedures
+    - 13.5.1 SRF connect procedures
+    - 13.5.2 SRF end-user interaction procedures
+    - 13.5.3 SRF disconnection procedures
+    - 13.5.4 Examples illustrating Complete User Interaction Sequences
+- 14 SDF application entity procedures
+  - 14.1 General
+  - 14.2 Model and interfaces
+  - 14.3 The SDF FSM structure
+  - 14.4 SDF state transition models
+    - 14.4.1 SDF state transition model for SCF-related states
+    - 14.4.2 SDF state transition model for SDF-related states
+- 15 CUSF application entity procedures
+  - 15.1 General
+  - 15.2 Model and interfaces
+    - 15.2.1 Background for the modelling and protocol
+    - 15.2.2 Modelling and protocol
+  - 15.3 Relations between CUSF FSM and the SSF/CCF and maintenance functions
+
+- 15.4 CUSF management finite state model (CUSME FSM)
+- 15.5 CUSF state transition diagram
+  - 15.5.1 State a: Idle
+  - 15.5.2 State b: Waiting For Instructions
+  - 15.5.3 State c: Monitoring
+- 16 Error procedures
+  - 16.1 Operation related error procedures
+    - 16.1.1 AttributeError
+    - 16.1.2 Cancelled
+    - 16.1.3 CancelFailed
+    - 16.1.4 DSAREferral
+    - 16.1.5 ETCFailed
+    - 16.1.6 ExecutionError
+    - 16.1.7 ImproperCallerResponse
+    - 16.1.8 MissingCustomerRecord
+    - 16.1.9 MissingParameter
+    - 16.1.10 Name Error
+    - 16.1.11 ParameterOutOfRange
+    - 16.1.12 Referral
+    - 16.1.13 RequestedInfoError
+    - 16.1.14 ScfReferral
+    - 16.1.15 Security
+    - 16.1.16 Service
+    - 16.1.17 Shadow
+    - 16.1.18 SystemFailure
+    - 16.1.19 TaskRefused
+    - 16.1.20 UnavailableResource
+    - 16.1.21 UnexpectedComponentSequence
+    - 16.1.22 UnexpectedDataValue
+    - 16.1.23 UnexpectedParameter
+    - 16.1.24 UnknownLegID
+    - 16.1.25 UnknownResource
+    - 16.1.26 Update
+    - 16.1.27 ChainingRefused
+    - 16.1.28 DirectoryBindError
+    - 16.1.29 ScfBindFailure
+    - 16.1.30 ScfTaskRefused
+  - 16.2 Entity-related error procedures
+    - 16.2.1 Expiration of T<sub>SSF</sub>
+    - 16.2.2 Expiration of T<sub>SRF</sub>
+    - 16.2.3 Expiration of T<sub>CUSF</sub>
+- 17 Detailed operation procedures
+  - 17.1 ActivateServiceFiltering procedure
+  - 17.2 ActivationReceivedAndAuthorized procedure
+  - 17.3 ActivityTest procedure
+  - 17.4 AddEntry procedure
+  - 17.5 AnalysedInformation procedure
+  - 17.6 AnalyseInformation procedure
+  - 17.7 ApplyCharging procedure
+  - 17.8 ApplyChargingReport procedure
+  - 17.9 AssistRequestInstructions procedure
+  - 17.10 AssociationReleaseRequested procedure
+  - 17.11 AuthorizeTermination procedure
+  - 17.12 CallGap procedure
+  - 17.13 CallInformationReport procedure
+  - 17.14 CallInformationRequest procedure
+  - 17.15 Cancel procedure
+  - 17.16 CancelStatusReportRequest procedure
+
+17.17 chainedAddEntry procedure  
+ 17.18 ChainedConfirmedNotificationProvided procedure  
+ 17.19 ChainedConfirmedReportChargingInformation procedure  
+ 17.20 ChainedEstablishChargingRecord procedure  
+ 17.21 chainedExecute procedure  
+ 17.22 ChainedHandlingInformationRequest procedure  
+ 17.23 ChainedHandlingInformationResult procedure  
+ 17.24 chainedModifyEntry procedure  
+ 17.25 ChainedNetworkCapability procedure  
+ 17.26 ChainedNotificationProvided procedure  
+ 17.27 ChainedReportChargingInformation procedure  
+ 17.28 ChainedProvideUserInfo procedure  
+ 17.29 chainedRemoveEntry procedure  
+ 17.30 ChainedRequestNotification procedure  
+ 17.31 chainedSearch procedure  
+ 17.32 CollectedInformation procedure  
+ 17.33 CollectInformation procedure  
+ 17.34 ComponentReceived procedure  
+ 17.35 ConfirmedNotificationProvided procedure  
+ 17.36 ConfirmedReportChargingInformation procedure  
+ 17.37 Connect procedure  
+ 17.38 ConnectToResource procedure  
+ 17.39 Continue procedure  
+ 17.40 ContinueWithArgument procedure  
+ 17.41 CoordinateShadowUpdate procedure  
+ 17.42 CreateCallSegmentAssociation procedure  
+ 17.43 in-directoryBind procedure  
+ 17.44 DirectoryUnbind procedure  
+ 17.45 DisconnectForwardConnection procedure  
+ 17.46 DisconnectForwardConnectionWithArgument procedure  
+ 17.47 DisconnectLeg procedure  
+ 17.48 dSABind procedure  
+ 17.49 DSAShadowBind procedure  
+ 17.50 in-DSAShadowUnbind procedure  
+ 17.51 EntityReleased Procedure  
+ 17.52 EstablishChargingRecord procedure  
+ 17.53 EstablishTemporaryConnection procedure  
+ 17.54 EventNotificationCharging procedure  
+ 17.55 EventReportBCSM procedure  
+ 17.56 EventReportFacility procedure  
+ 17.57 Execute procedure  
+ 17.58 FacilitySelectedAndAvailable procedure  
+ 17.59 FurnishChargingInformation procedure  
+ 17.60 HandlingInformationRequest procedure  
+ 17.61 HandlingInformationResult procedure  
+ 17.62 HoldCallInNetwork procedure  
+ 17.63 in-DSAUnbind procedure  
+ 17.64 InitialDP procedure  
+ 17.65 InitiateAssociation procedure  
+ 17.66 InitiateCallAttempt procedure  
+ 17.67 ManageTriggerData procedure  
+ 17.68 MergeCallSegments procedure  
+ 17.69 ModifyEntry procedure
+
+17.70 MoveCallSegments procedure  
+ 17.71 MoveLeg procedure  
+ 17.72 NetworkCapability procedure  
+ 17.73 NotificationProvided procedure  
+ 17.74 OAbandon procedure  
+ 17.75 OAnswer procedure  
+ 17.76 OCalledPartyBusy procedure  
+ 17.77 ODisconnect procedure  
+ 17.78 OMidCall procedure  
+ 17.79 ONoAnswer procedure  
+ 17.80 OriginationAttempt procedure  
+ 17.81 OriginationAttemptAuthorized procedure  
+ 17.82 OSuspended procedure  
+ 17.83 PlayAnnouncement procedure  
+ 17.84 PromptAndCollectUserInfoInformation procedure  
+ 17.85 PromptAndReceiveMessage procedure  
+ 17.86 ProvideUserInfoInformation procedure  
+ 17.87 Reconnect procedure  
+ 17.88 ReleaseAssociation procedure  
+ 17.89 ReleaseCall procedure  
+ 17.90 RemoveEntry procedure  
+ 17.91 ReportChargingInformation procedure  
+ 17.92 ReportUTSI procedure  
+ 17.93 RequestCurrentStatusReport procedure  
+ 17.94 RequestEveryStatusChangeReport procedure  
+ 17.95 RequestFirstStatusMatchReport procedure  
+ 17.96 RequestNotification procedure  
+ 17.97 RequestNotificationChargingEvent procedure  
+ 17.98 RequestReportBCSMEVENT procedure  
+ 17.99 RequestReportBCUSMEVENT procedure  
+ 17.100 RequestReportFacilityEvent procedure  
+ 17.101 RequestReportUTSI procedure  
+ 17.102 RequestShadowUpdate procedure  
+ 17.103 ResetTimer procedure  
+ 17.104 RouteSelectFailure procedure  
+ 17.105 SCFBind procedure  
+ 17.106 scfBind procedure (in the chaining case)  
+ 17.107 SCFUnBind procedure  
+ 17.108 scfUnBind procedure (in the chaining case)  
+ 17.109 ScriptClose procedure  
+ 17.110 ScriptEvent procedure  
+ 17.111 ScriptInformation procedure  
+ 17.112 ScriptRun procedure  
+ 17.113 Search procedure  
+ 17.114 SelectFacility procedure  
+ 17.115 SelectRoute procedure  
+ 17.116 SendChargingInformation procedure  
+ 17.117 SendComponent procedure  
+ 17.118 SendFacilityInformation procedure  
+ 17.119 SendSTUI procedure  
+ 17.120 ServiceFilteringResponse procedure
+
+- 17.121 SpecializedResourceReport procedure
+- 17.122 SplitLeg procedure
+- 17.123 StatusReport procedure
+- 17.124 TAnswer procedure
+- 17.125 TBusy procedure
+- 17.126 TDisconnect procedure
+- 17.127 TerminationAttempt procedure
+- 17.128 TermAttemptAuthorized procedure
+- 17.129 TMidCall procedure
+- 17.130 TNoAnswer procedure
+- 17.131 TSuspended procedure
+- 17.132 UpdateShadow procedure
+- 18 Services assumed from Lower Layers
+  - 18.1 Services assumed from TCAP
+    - 18.1.1 Common procedures
+    - 18.1.2 SSF-SCF interface
+    - 18.1.3 SCF-SRF interface
+    - 18.1.4 SCF-CUSF interface
+    - 18.1.5 SCF-SCF interface
+    - 18.1.6 SCF-SDF interface
+    - 18.1.7 SDF-SDF interface
+  - 18.2 Services assumed from SCCP
+    - 18.2.1 Normal procedures
+    - 18.2.2 Service functions from SCCP
+- 19 IN generic interface security
+  - 19.1 Interface security requirements
+    - 19.1.1 Data confidentiality
+    - 19.1.2 Data integrity and data origin authentication
+    - 19.1.3 Key management
+  - 19.2 Procedures and algorithms
+    - 19.2.1 Authentication procedures
+    - 19.2.2 SPKM algorithms and negotiation
+    - 19.2.3 Three-way mutual authentication
+    - 19.2.4 Assignment of credentials
+  - 19.3 Mapping of security information flow definitions to tokens
+  - 19.4 Security FSM definitions
+    - 19.4.1 Two-way mutual authentication FSMs
+    - 19.4.2 Three-way mutual authentication FSMs
+- Annex A.1 – Introduction to the INAP CS-1 and CS-2 SDL models
+  - A.1.1 Introduction
+  - A.1.2 Example for the interworking of the SSF/CCF SDL processes
+  - A.1.3 Example for the Three-Party Call setup as seen from the environment
+- Annex A.2 – Transition diagrams
+  - A.2.1 Call Segment Association transition diagram
+  - A.2.2 Call Segment transition diagram
+- Annex A.3 – SDL Specification of CS-1 SSF/CCF
+- Annex A.4 – SDL Specification of CS-2 extensions to SSF/CCF
+- Annex A.5 – SDL Specification of CS-2 SRF
+- Annex A.6 – SDL Specification of CS-2 Assist/Hand-off SSF
+- Annex A.7 – SDL Specification of CS-2 CUSF
+- Annex A.8 – SDL Specification of CS-2 SCF
+
+Appendix I – Expanded ASN.1 source
+
+Appendix II – Data modelling
+
+- II.1 Introduction
+  - II.1.1 Purpose and scope
+  - II.1.2 Assumptions
+    - II.1.2.1 Mobility service and subscriber identifiers
+    - II.1.2.2 Disclosure of profile entries
+- II.2 Directory Information Tree (DIT) schema
+  - II.2.1 X.500 DIT
+    - II.2.1.1 Location of local profiles
+    - II.2.1.2 Location of remote subscriber profiles
+    - II.2.1.3 Location of locally visiting subscriber profiles
+    - II.2.1.4 Reducing message flow
+  - II.2.2 Object classes
+    - II.2.2.1 inMobilityUserProfile
+    - II.2.2.2 inMobilityServiceProvider
+    - II.2.2.3 inMobilitySubscriberGroup
+  - II.2.3 Attribute types
+    - II.2.3.1 inMobilityID
+    - II.2.3.2 inMobilityPIN
+    - II.2.3.3 inMobilityPrefix
+    - II.2.3.4 inMobilitySubPrefix
+  - II.2.4 DIT structure definition
+    - II.2.4.1 Name forms
+    - II.2.4.2 Structure rules
+    - II.2.4.3 Object identifier assignments
+
+Appendix III – Examples of SPKM algorithms for IN CS-2
+
+- III.1 General
+- III.2 Integrity Algorithm (I-ALG)
+  - III.2.1 Example-1
+  - III.2.2 Example-2
+  - III.2.3 Example-3
+  - III.2.4 Example-4
+- III.3 Confidentiality Algorithm (C-ALG)
+  - III.3.1 Example-1
+- III.4 Key Establishment Algorithm (K-ALG)
+  - III.4.1 Example-1
+  - III.4.2 Example-2
+  - III.4.3 Example-3
+- III.5 One-Way Function (O-ALG) for Subkey Derivation Algorithm
+  - III.5.1 Example-1
+
+**Q.1229 – Users’ Guide for Intelligent Network Capability Set 2<sup>1</sup>**
+
+---
+
+<sup>1</sup> Presently in the stage of draft.
+
+## ITU-T RECOMMENDATIONS SERIES
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of the ITU-T                                                                                          |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| Series F        | Non-telephone telecommunication services                                                                                       |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Transmission of television, sound programme and other multimedia signals                                                       |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| <b>Series Q</b> | <b>Switching and signalling</b>                                                                                                |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| Series Y        | Global information infrastructure                                                                                              |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |

marked/Q/T-REC-Q.1301-199510-I_PDF-E/raw.md

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+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**Q.1301**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(10/95)
+
+**INTELLIGENT NETWORK**
+
+---
+
+**TELECOMMUNICATION APPLICATIONS  
+FOR SWITCHES AND COMPUTERS (TASC) –  
+TASC ARCHITECTURE**
+
+**ITU-T Recommendation Q.1301**
+
+(Previously "CCITT Recommendation")
+
+---
+
+# FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
+
+The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation Q.1301 was prepared by ITU-T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 17th of October 1995.
+
+---
+
+# NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# CONTENTS
+
+*Page*
+
+|       |                                            |    |
+|-------|--------------------------------------------|----|
+| 1     | Introduction .....                         | 1  |
+| 2     | Scope .....                                | 1  |
+| 3     | References .....                           | 1  |
+| 4     | Terms and Definitions .....                | 2  |
+| 4.1   | Abbreviations .....                        | 2  |
+| 5     | Architecture .....                         | 2  |
+| 5.1   | Domains .....                              | 2  |
+| 5.1.1 | Domain .....                               | 2  |
+| 5.1.2 | Call views .....                           | 3  |
+| 6     | Call monitoring .....                      | 6  |
+| 6.1   | Introduction .....                         | 6  |
+| 6.2   | CE monitoring versus call monitoring ..... | 6  |
+| 6.3   | Call monitoring operation .....            | 6  |
+| 7     | TASC interfaces .....                      | 7  |
+| 7.1   | Single TASC interface .....                | 7  |
+| 7.2   | Multiple TASC interfaces .....             | 7  |
+| 8     | TASC switching model .....                 | 8  |
+| 8.1   | TASC objects .....                         | 8  |
+| 8.1.1 | Communication Entity .....                 | 8  |
+| 8.1.2 | Line CE .....                              | 9  |
+| 8.1.3 | Distribution CE .....                      | 10 |
+| 8.2   | Communication Party .....                  | 11 |
+| 8.2.1 | Description and behaviour .....            | 11 |
+| 8.2.2 | Types .....                                | 11 |
+| 8.2.3 | Line CP .....                              | 11 |
+| 8.2.4 | Distribution CP .....                      | 12 |
+| 8.3   | User .....                                 | 13 |
+| 8.3.1 | Description and Behaviour .....            | 13 |
+| 8.3.2 | Types .....                                | 13 |
+| 8.3.3 | Registered User .....                      | 14 |
+| 8.3.4 | Non-Registered User .....                  | 15 |
+| 8.4   | Call View .....                            | 16 |
+| 8.4.1 | Originating Call View .....                | 16 |
+| 8.4.2 | Terminating Call View .....                | 16 |
+| 8.4.3 | Incoming Distribution Call View .....      | 17 |
+| 9     | Call view states .....                     | 18 |
+| 9.1   | Call View State descriptions .....         | 18 |
+| 9.1.1 | Originating states .....                   | 18 |
+| 9.1.2 | Terminating Call View States .....         | 20 |
+| 9.1.3 | Incoming Distribution Call View .....      | 21 |
+| 9.1.4 | Agent model .....                          | 22 |
+
+# **SUMMARY**
+
+This Recommendation identifies the Architecture that supports TASC (Telecommunication Applications for Switches and Computers) and is one in the Q.1300-Series Recommendations on TASC. The main purpose of TASC is to allow applications running within the network user's environment to integrate telecommunication services with computing facilities. This would typically allow business applications to use TASC to integrate the computer workstation and telephone at the user's desktop. This Recommendation does not define how the elements of the architecture are implemented. Part of the definition of the TASC architecture includes the TASC objects which are the basis for the TASC Functional Services.
+
+# **INTRODUCTION**
+
+The concept of TASC, which this architecture supports, is described in Recommendation Q.1300, TASC Overview. Although the TASC architecture identifies, describes and models interactions between the TASC objects, it does not specify how they should be implemented. In addition to call and telecommunication device objects, the role of Agents (as in ACD system) is modelled.
+
+# **BACKGROUND**
+
+This Recommendation is based on the experience of ECMA (Standardising Information and Communication Systems) and ANSI (American National Standards Institute) member companies in developing switch-to-computer interfaces and takes directions from CSTA (Computer Supported Telecommunications Application) and SCAI (Switch-to-Computer Application Interface) standards.
+
+# **KEYWORDS**
+
+Architecture, Models, Objects, TASC.
+
+# **TELECOMMUNICATION APPLICATIONS FOR SWITCHES AND COMPUTERS (TASC) – TASC ARCHITECTURE**
+
+*(Geneva, 1995)*
+
+# **1 Introduction**
+
+This Recommendation defines the architecture for TASC and identifies the various objects which represent information which the TASC interface operates on. The concept behind TASC is described in Recommendation Q.1300, which is considered essential reading prior to this Recommendation, and the services that the architecture supports are defined in Recommendation Q.1302. Recommendation Q.1303 defines the requirements for managing the objects herein described.
+
+# **2 Scope**
+
+This Recommendation defines an architecture for the support of Telecommunication Applications of Switches and Computers. The architecture supports the communication between the switch and computer and the services conveyed by that communication. This Recommendation considers how the information communicated is represented. TASC does not define how the aspects making up TASC in either the switch or computer environment are implemented.
+
+The emphasis of TASC has been to define third-party call control functions which also encompasses first-party call control. TASC is independent of any underlying mechanism and is applicable to public, private and hybrid networks. TASC is designed to be flexible in order to support other communication environments in addition to those based upon ISDN and Intelligent Network (IN) principles.
+
+It is focused on providing an application service interface between a switch and computer.
+
+TASC supports both a single-ended call (originating and terminating) view as well as a global call view.
+
+The TASC architecture accommodates different ways of viewing calls available in implementations but models these views on stable and accepted models of how calls work.
+
+# **3 References**
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
+
+- ITU-T Recommendation Q.1300 (1995), *Telecommunication Applications for Switches and Computers (TASC) – General overview*.
+- ITU-T Recommendation Q.1302 (1995), *Telecommunication Applications for Switches and Computers (TASC) – TASC Functional services*.
+- ITU-T Recommendation Q.1303 (1995), *Telecommunication Applications for Switches and Computers (TASC) – TASC management: Architecture, methodology and requirements*.
+
+# 4 Terms and Definitions
+
+This Recommendation uses terms defined in Recommendation Q.1300.
+
+## 4.1 Abbreviations
+
+For the purposes of this Recommendation, the following abbreviations are used:
+
+|      |                                                           |
+|------|-----------------------------------------------------------|
+| ACD  | Automatic Call Distributor                                |
+| CE   | Communication Entity                                      |
+| CP   | Communication Party                                       |
+| CV   | Call View                                                 |
+| FS   | Functional Service                                        |
+| OCV  | Originating Call View                                     |
+| TASC | Telecommunication Applications for Switches and Computers |
+| TCV  | Terminating Call View                                     |
+
+# 5 Architecture
+
+The TASC Architecture provides a framework for communication between a computer and a switch. Recommendation Q.1300 describes the environments in which TASC may be used.
+
+## 5.1 Domains
+
+Domains identify the area that TASC may manipulate and influence.
+
+### 5.1.1 Domain
+
+Call domains ultimately deal with controllable and visible telecommunication devices in TASC's problem space. Such devices are referred to as Communication Entities (CE) so as to avoid confusion with connotations of specific types of devices.
+
+#### 5.1.1.1 Control and visibility
+
+TASC deals with the control and visibility of calls as they originate and terminate at CEs. All TASC functions revolve around this fundamental principle. Therefore, the problem space involves calls which can originate, terminate, or become visible at CEs. The CEs defined by TASC include Line CEs and Distribution CEs.
+
+When dealing with a call the switch is transparent to the application. TASC does not attempt to directly control or provide visibility of switches and computers. So switch and computer objects are not in the TASC problem space. Only the CEs related to or attached to switches and computers involved in the calls are visible.
+
+#### 5.1.1.2 Objects of interest
+
+TASC consists of a set of functional services that provide peer-to-peer applications with a standard means of communication for the control and visibility of calls. Ultimately it is the peer-to-peer applications which know the objects of interest. Peer-to-peer applications not only have a communication application context, but they also have a common, and agreed, set of CEs in the object space. In other words, the two applications know the CEs over which they have control and visibility. This object space is either statically or dynamically defined. The locations of the objects are transparent to TASC. This is depicted in Figure 1 below.
+
+![Diagram illustrating the transparent location of CEs. A Computer and a Switch are shown, each containing an Application and a TASC component. The Applications are connected to the TASC components, which are in turn connected to a central TASC component. The central TASC component is connected to a circle labeled 'Operation Domain' containing three CEs (CE 1, CE 2, CE 3). Arrows indicate 'Physical communication' between the TASC components and the CEs. A note states 'Object location is transparent to TASC'. A reference code 'T1168020-94/d01' is present.](fc46871d72c65d3381d9201646d23439_img.jpg)
+
+The diagram shows a 'Computer' box containing an 'Application' and a 'TASC' (oval). The 'Application' is connected to the 'TASC'. Below the 'Computer' box is another 'TASC' (oval). To the right is a 'Switch' box containing an 'Application' and a 'TASC' (oval). The 'Application' is connected to the 'TASC'. Below the 'Switch' box is another 'TASC' (oval). A central 'TASC' (oval) is connected to the 'TASC' in the 'Computer', the 'TASC' in the 'Switch', and the 'TASC' below the 'Computer'. Below the central 'TASC' is a circle labeled 'Operation Domain' containing three boxes labeled 'CE 1', 'CE 2', and 'CE 3'. Arrows point from the central 'TASC' to each of the 'CE' boxes. A double-headed arrow labeled 'Physical communication' connects the 'TASC' below the 'Computer' and the 'TASC' below the 'Switch'. A note with an arrow pointing to the 'Operation Domain' circle states 'Object location is transparent to TASC'. In the bottom right corner, the text 'T1168020-94/d01' is present.
+
+Diagram illustrating the transparent location of CEs. A Computer and a Switch are shown, each containing an Application and a TASC component. The Applications are connected to the TASC components, which are in turn connected to a central TASC component. The central TASC component is connected to a circle labeled 'Operation Domain' containing three CEs (CE 1, CE 2, CE 3). Arrows indicate 'Physical communication' between the TASC components and the CEs. A note states 'Object location is transparent to TASC'. A reference code 'T1168020-94/d01' is present.
+
+FIGURE 1/Q.1301  
+**Transparent Location of CEs**
+
+#### 5.1.1.3 Operation and working domains
+
+The identification of CEs of interest to an application may occur through static (subscription arrangements) and dynamic means (messaging). The identified CEs are the operation domain for a particular application. Once that application has begun processing, the transitional objects such as CVs (calls views), CPs (connections between CEs and calls), and Users may be created and destroyed as a result of TASC related activity. The working domain may expand or contract during the lifetime of the application but may not expand to include CEs outside of the defined operation domain. It is the set of CEs (objects) which can be monitored by an application which form a Working Domain. The relationship between Operation and Working Domain is illustrated in Figure 2.
+
+TASC does not provide the ability for applications to acquire and lock the use of a CE for the exclusive use of a particular application process. Therefore coordination of applications and their use of CEs is outside the scope of TASC.
+
+For example, in a customer service department for a company which has agents and an ACD system, the object space for the application is the set of objects representing the agent CEs and ACD pilot numbers where calls are originated, terminated, or become visible. This Operation Domain does not include end users (i.e. the customers' phones), external phones where service calls are originated, or the switches or computers. The objects which can be monitored are the agent CEs and pilot numbers, and these represent the domain of objects of interest in the calls. This object space is defined for, and known by, the peer-to-peer applications. The locations of the objects are transparent to TASC. The objects actually monitored form the Working Domain.
+
+### 5.1.2 Call views
+
+TASC defines a call view object to represent a call in the problem space. A call view has a call view identifier, a call view state, and participants or parties. The call view identifier is unique within the Operation domain. That is, in the communication between the peer applications, the Call View ID identifies a unique call. No two calls visible to the peer applications may have the same Call view ID.
+
+![Diagram illustrating the relationship between the Operation Domain and the Working Domain for a single call. The Operation Domain is a large circle containing several 'CE' (Call Element) boxes. The Working Domain is a smaller circle within the Operation Domain. The Call Monitor Domain (global view) is a dashed rectangle enclosing some CEs. Individual Device Monitor Domains (single-ended view) are dotted circles around specific CEs. Lines connect CEs to show their involvement in the life of a single call.](3121ebddccf183ca63bb9781be440a7e_img.jpg)
+
+The diagram shows a large circle labeled 'Operation Domain'. Inside it, a dashed rectangle labeled 'Call Monitor Domain (global view)' contains three 'CE' boxes. A smaller circle labeled 'Working Domain' is also inside the Operation Domain. Within the Working Domain, there are three 'CE' boxes, each enclosed in a dotted circle labeled 'Individual Device Monitor Domains (single-ended view)'. Lines connect various 'CE' boxes, with a label 'CE's involved in the life of a single call' pointing to one of the connections.
+
+Diagram illustrating the relationship between the Operation Domain and the Working Domain for a single call. The Operation Domain is a large circle containing several 'CE' (Call Element) boxes. The Working Domain is a smaller circle within the Operation Domain. The Call Monitor Domain (global view) is a dashed rectangle enclosing some CEs. Individual Device Monitor Domains (single-ended view) are dotted circles around specific CEs. Lines connect CEs to show their involvement in the life of a single call.
+
+T1168030-94/d02
+
+FIGURE 2/Q.1301  
+Operation and working domain
+
+#### 5.1.2.1 Single-ended view
+
+The single-ended view of a call is the view of call progress and call states from a CE's perspective. The TASC object model for a two-party call splits into originating and terminating views. For example, for a basic call, when that CE is originating a call, the switch provides the single-ended view incorporating the originating call model events. The actions of the terminating side are implied in those events. When that CE is terminating a call, the switch provides the single-ended view incorporating the terminating call model events. The actions of the originating side are implied in those events but cannot be guaranteed. Information available about that CE and other CEs in the call is made available in the single-ended view by the switch.
+
+Single-ended views are independent of each other. A switch may allocate separate call view identifiers for each single-ended view.
+
+#### 5.1.2.2 Monitoring within a single-ended view
+
+TASC defines a single-ended view for the associated CE. This means that TASC defines call events which are reported for calls based on whether the call is originating, terminating or distributing at the CE. Thus if a CE is being monitored and a call terminates at the CE, the terminating call events may be reported. If a CE is being monitored and a call originates at the CE, the originating call events may be reported. Events may also be reported for monitored CEs at which calls appear such as Distribution CEs.
+
+#### 5.1.2.3 Global view
+
+An alternative to the single-ended view is the global view where the view of call progress and call states are from the domain's perspective of a call. Thus all parties associated with a specific call can be visible with a global call view. Each party associated with the call still needs to adhere to the relevant basic call model (originating/terminating or distribution) but are united by a common identifier for the call.
+
+The extent of a global call is limited by the operation domain, thus a call that goes outside of the Operation Domain may only be able to support a single-ended view in some circumstances.
+
+#### 5.1.2.4 Monitoring within a global view
+
+The method used to invoke device and call monitoring differs but the event reports generated remain the same. With device monitoring, events are generated as a result of a change in the Call View state currently at the monitored device. With call monitoring, events are generated as a result of Call View state changes anywhere within the call. Two forms of Call Monitoring are defined within TASC:
+
+- 1) A Call Monitor set on a call will generate events as a result of Call View state changes anywhere within the call. A call where some CEs are outside the TASC operation domain may report less call progress information; at least one CE must reside within the Operation Domain for call monitoring to function. This type of monitor will follow a single call. It may only be invoked once the call has been created and a Call View ID returned to the application, e.g. after a TASC Make Call Functional Service request or Call-Arrived event (see Recommendation Q.1302).
+- 2) A Call Monitor set on a CE will generate events as a result of a Call View state change for every call that has involved the specified CE since the call monitor was invoked. A call where some CEs are outside the TASC operation domain may report less call progress information; at least one CE must reside within the Operation Domain for call monitoring to function. This type of monitor will follow all calls which have contact with the specified CE, e.g. a call monitor on a distribution CE will monitor all calls which are distributed by that CE. Events will be generated during the complete life of each call distributed.
+
+Call monitoring is considered further in clause 6.
+
+#### 5.1.2.5 Calls between CEs
+
+As calls originate, arrive, terminate and disappear from CEs within the working domain, events are reported based on the single-ended view, features in effect, and characteristics of a CE. Since all calls are uniquely identified by a Call View ID, any and all events which specify the same Call View ID in the communication protocol between the peer applications refer to the same call. The switches assign and manage Call IDs although a management function may manipulate these ID's as described in Recommendation Q.1303
+
+#### 5.1.2.6 Call view ID
+
+Call IDs are assigned and managed by the switch and must uniquely identify calls at CEs. These Call IDs must be unique within the Working Domain between peer applications. How the switch assigns Call IDs to calls between CEs in the operation domain (i.e. whether or not it uses the same Call view ID for both originating and terminating objects and events) must be understood and known by the applications prior to association. Thus Call view ID assignment is part of the application rules and in part a function of the type of network – public, private or hybrid. It should be noted that a request for a global call view may be rejected based upon the capabilities of the signalling environment in which the applications exists.
+
+#### 5.1.2.7 Global call view ID
+
+In a call between two CEs in a working domain, a Global Call is characterized by the same Call View ID being assigned for both originating, terminating and distributing endpoints. The Call view ID is unique in the Working Domain.
+
+Management of identifiers is achieved via parameters included in Functional Service responses and Event Reports. Identifiers cease to be valid when their context vanishes. If a call ends, its Call View Identifier is no longer valid to refer to that call.
+
+If a call changes its Call View Identifier when a Conference or Transfer occurs, identifiers are provided to link the old Call View Identifier to the new Call View Identifier. Similarly, if a CE Identifier is changed identifiers are provided to link new and old identifiers. Event Reports are used to report state changes.
+
+Identifiers can be re-used. Once an identifier has lost its context, it may be re-used to identify another object.
+
+Note that it is recommended that implementations do not re-use identifiers prematurely.
+
+Individual Call View and CE Identifiers are not guaranteed to be globally unique. TASC requires that the combination of Call View and CE Identifier be globally unique within an operation domain. To accomplish this, either the Call View Identifier, or the CE Identifier (or both) shall be globally unique.
+
+# **6 Call monitoring**
+
+## **6.1 Introduction**
+
+Call Monitoring is a Functional Service which will provide call progress information for all Communication Entities (CEs) involved in a call. During the life of a call, regardless of the operations performed on that call, this service will continue to provide call progress information for as long as the call remains within the TASC Operation Domain. Call Monitoring will continue to provide call progress information after transfers, forwarding and conference operations.
+
+## **6.2 CE monitoring versus call monitoring**
+
+CE monitoring will report call progress information while a call resides at CEs which have active CE monitors; this is known as the TASC Working Domain. The collection of CEs on which these monitors have been placed remains fairly static; they are not changed by any particular call. An application using CE monitoring must therefore define precisely the CEs from which it wishes to receive call progress information. The complete collection of CEs on which an application may set monitors is known as the TASC Operation Domain.
+
+During the life of a single call many CEs may participate; some with active CE monitors and some without. An application may therefore wish to invoke a monitor which will report call progress information throughout the life of a call, regardless of the CEs which are involved in that call. Call Monitoring will provide an application with this information without having to explicitly place monitors on all the CEs which have participated in that call. With Call Monitoring, the domain of the monitor changes very dynamically to include the collection of CEs involved during the life of a particular call. Figure 2 illustrates the relationship between the various TASC domains.
+
+The TASC Operation Domain is the collection of CEs on which an application may place a monitor. The TASC Working Domain represents the collection of CEs within the Operation Domain on which an application has placed CE monitors independently of any particular call. The Call Monitor Domain is the collection of CEs within the Operation Domain which participate in a single call when call monitoring has been enabled. There will be a Call Monitor Domain, dynamically changing as the call progresses, for each call monitor invoked. When a call dies, then its associated call monitor domain also dies. The Call Monitoring domain is only constrained by the Operation Domain and operates independently from the Working Domain but may include CEs within the Working Domain. When a CE monitor is invoked then the domain of that monitor is restricted to the individual CE, i.e. the individual CE monitor domain.
+
+## **6.3 Call monitoring operation**
+
+TASC Functional Services such as Transfer, Conference and Forwarding (see Recommendation Q.1302) will not prevent a Call monitor from following the call even if the Call View ID changes. A Call Monitor identifier will be included in each event reported.
+
+For a Call Monitor set on a CE a Call Monitor identifier will be returned. This Call Monitor identifier will be reported for all calls which involve that CE while the Call monitor is active. This Call Monitor identifier is distinct from any CE Monitor identifier. As an example, a Call Monitor placed upon a Distribution CE will generate call progress events for all calls which are distributed by that distribution CE and will use the same Call Monitor identifier.
+
+# 7 TASC interfaces
+
+## 7.1 Single TASC interface
+
+A single viewing point covers scenarios where there is a single TASC interface. There is a single switch, a single computer, and a single application context instance. The computer thus has control and visibility of calls from a single point. However, the operation domain of CEs which can be monitored may all be local, all remote, or mixed between local and remote.
+
+## 7.2 Multiple TASC interfaces
+
+Multiple viewing points exist when there are multiple TASC interfaces for the same operation domain. This may involve multiple interfaces between a single switch and a single computer or multiple interfaces with multiple switches and computers. The scenario calls for a common domain of CEs known by all applications on which monitors can be placed. There are many peer-to-peer applications operating in a cooperative manner. However, in order to cooperate they all share a common definition of the operation domain which can be monitored. The operation domain of CEs which can be monitored may all be local to a single switch or distributed between switches.
+
+There may be proprietary communication links between computers, between switches, and/or between computers and switches, to facilitate coordination and information flow. These links and information exchange are outside the scope of TASC. See Figure 3.
+
+![Diagram illustrating multiple TASC interfaces and their interaction with an operation domain.](5e92d9e8e9ce204e405bff2367f88176_img.jpg)
+
+The diagram shows a network architecture with multiple components. At the top, 'Computer M' and 'Switch N' are shown. Each contains an 'Application' box connected to a 'TASC' circle. A thick horizontal line connects the 'Application' in Computer M to the 'Application' in Switch N. Below this, 'Computer 1' and 'Switch 1' are shown in a similar configuration. A thick horizontal line connects the 'Application' in Computer 1 to the 'Application' in Switch 1. Both 'Computer 1' and 'Switch 1' have multiple overlapping boxes behind them, representing multiple instances. At the bottom, a double-headed arrow labeled 'Physical Communication' connects the 'TASC' in Computer 1 and the 'TASC' in Switch 1. On the right, a large circle labeled 'Operation Domain' contains three boxes labeled 'CE 1', 'CE 2', and 'CE 3'. Dotted lines connect the 'TASC' in Computer 1, the 'TASC' in Switch 1, the 'TASC' in Computer M, and the 'TASC' in Switch N to this 'Operation Domain'. A text label 'Object location is transparent to TASC' is near the 'Operation Domain'. A text label 'Call IDs must be unique in the information flow between peer applications' is near the top left. A small code 'T1168040-94/d03' is in the bottom right corner of the diagram area.
+
+Diagram illustrating multiple TASC interfaces and their interaction with an operation domain.
+
+FIGURE 3/Q.1301  
+Cooperating Applications
+
+In both ways of viewing calls identified in this Recommendation, the following is true:
+
+A call between two CEs in the operation domain is a Global Call view ID if the same Call view ID is assigned for both the originating and terminating events.
+
+The locations of the CEs are transparent to TASC. If a CE does not reside on the local switch, capabilities outside of TASC must exist to place a monitor on this 'remote' CE, signalling must exist to facilitate information flow between switches or computers, and global Call view ID management (i.e. management of Call view IDs between multiple switches) must be defined and provided. This is a function of the scope of the application, the type of network (public, private), and network capabilities.
+
+In a single interface, all CEs are viewed and controlled over a single interface regardless of location. With multiple interfaces, CEs may be viewed and controlled from multiple points but the views at all points are considered with Global Call IDs.
+
+### **In summary**
+
+- 1) TASC supports the following concepts: Operation Domain, Working Domains, Single-ended Calls View and Global Call Views.
+- 2) Operation Domains are defined prior to application initiation. Working Domains are identified by dynamic means and may include a subset of those CEs which were identified as members of the Operation domain.
+- 3) The physical locations of monitored CEs are transparent to TASC.
+- 4) A Global Call View is a function of Call view ID management and assignment and thus a function of the switch, application, and/or network. Call view ID management is implementation specific. TASC provides the flexibility to support different Call view ID management schemes.
+- 5) TASC does not define standardized signalling or information flow between applications in a distributed environment to facilitate coordination and control of calls across multiple TASC interfaces. However, TASC provides the basic information necessary to facilitate that coordination and control.
+
+# **8 TASC switching model**
+
+The TASC switching model provides an abstract view of switching objects and their behaviour. This switching model consists of TASC objects, their models, and their relationships.
+
+## **8.1 TASC objects**
+
+The following objects for TASC have been identified (see Figure 4):
+
+**Communication Entity (CE)** – An entity that originates, terminates, or becomes visible in a call.
+
+**User** – An entity that makes use of a CE (e.g. initiates a call or answers a call).
+
+**Call View (CV)** – An abstraction of a call which represents the progression of a Call at a CE from the standpoint of a CE involved in a call.
+
+**Communication Party (CP)** – An associative object that maintains the relationship between a call and CE.
+
+### **8.1.1 Communication Entity**
+
+#### **8.1.1.1 Description and behaviour**
+
+An entity that originates, terminates, or becomes visible in a call. Many users, calls, and CPs may be associated with each CE.
+
+#### **8.1.1.2 Types**
+
+**Line CE** – A component of a switch over which calls are originated from or terminated to a CE.
+
+**Distribution CE** – An entity that distributes calls to other CEs.
+
+![Diagram of TASC Objects showing a 'Global Call' within a 'Switch' box. The 'Global Call' is a large circle containing two 'CV' (Call View) circles. To the left of the 'Global Call' is a 'CE' (Control Element) rectangle, and to the right is another 'CE' rectangle. Below each 'CE' is a 'CP' (Control Point) circle. Arrows point from each 'CP' to its corresponding 'CE'. Outside the 'Switch' box, on both the left and right, are 'User' boxes connected to the 'CE' rectangles by horizontal lines.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+Diagram of TASC Objects showing a 'Global Call' within a 'Switch' box. The 'Global Call' is a large circle containing two 'CV' (Call View) circles. To the left of the 'Global Call' is a 'CE' (Control Element) rectangle, and to the right is another 'CE' rectangle. Below each 'CE' is a 'CP' (Control Point) circle. Arrows point from each 'CP' to its corresponding 'CE'. Outside the 'Switch' box, on both the left and right, are 'User' boxes connected to the 'CE' rectangles by horizontal lines.
+
+T1168050-94/d04
+
+FIGURE 4/Q.1301  
+TASC Objects
+
+### 8.1.2 Line CE
+
+#### 8.1.2.1 Description and behaviour
+
+A component of a switch over which calls are originated from or terminated to a user. See Figure 5.
+
+![Diagram of a Line CE within a 'Switch' box. It shows a 'CV' (Call View) circle on the left, a 'Line CE' rectangle in the center, and a 'CP' (Control Point) circle at the bottom. An arrow points from the 'CP' to the 'Line CE'. A horizontal line connects the 'Line CE' to a 'User' box outside the 'Switch' box on the right.](ddc7460821484f1ae2835c67955c554c_img.jpg)
+
+Diagram of a Line CE within a 'Switch' box. It shows a 'CV' (Call View) circle on the left, a 'Line CE' rectangle in the center, and a 'CP' (Control Point) circle at the bottom. An arrow points from the 'CP' to the 'Line CE'. A horizontal line connects the 'Line CE' to a 'User' box outside the 'Switch' box on the right.
+
+T1168060-94/d05
+
+FIGURE 5/Q.1301  
+Line CE
+
+The call related events are those events reported by transitions in the originating and terminating basic call view.
+
+#### 8.1.2.2 Attributes
+
+**Line Identifier** – Each Line CE has at least one unique identifier. Some Line CEs may have multiple identifiers.
+
+**Call View Identifiers** – One or more call view identifiers may be associated with each Line CE.
+
+**CP Identifiers** – One or more CP Identifiers may be associated with each Line CE. A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**User** – A user is associated with a Line CE.
+
+**State** – The condition of the Line CE is described by Enable, Disable, In-service, Out-of-service, etc.
+
+#### 8.1.2.3 Actions
+
+The actions associated with a Line CE are those provided by management (e.g. Enable, Disable) and those provided by user action (e.g. Set-Forwarding, Clear Forwarding, etc.).
+
+#### 8.1.2.4 Notifications
+
+The notifications associated with a Line CE are those provided by management (e.g. Enabled, Disabled) and those provided by user action (e.g. Forwarding-Set, Forwarding-Clear, etc.).
+
+### 8.1.3 Distribution CE
+
+#### 8.1.3.1 Description and behaviour
+
+An entity that distributes calls to other CEs.
+
+#### 8.1.3.2 Types
+
+**Incoming Distribution CE** – An entity that distributes calls to Line CEs and other incoming Distribution CEs.
+
+**Outgoing Distribution CE** – Not defined by this Recommendation.
+
+#### 8.1.3.3 Incoming Distribution CE
+
+##### 8.1.3.3.1 Description and Behaviour
+
+An entity that distributes calls to Line CEs or other Incoming Distribution CEs.
+
+The call related events are those events reported by transitions in the Incoming Distribution CE.
+
+##### 8.1.3.3.2 Attributes
+
+**Incoming Distribution CE Identifier** – Each Incoming Distribution CE has at least one unique identifier. Some Incoming Distribution CEs may have multiple identifiers.
+
+**Call View Identifiers** – One or more call view identifiers may be associated with each Incoming Distribution CE.
+
+**CP Identifiers** – One or more CP Identifiers may be associated with each Incoming Distribution CE. A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**CE Identifiers** – One or more Line or Incoming Distribution CE Identifiers to which calls are to be distributed may be associated with an Incoming Distribution CE.
+
+**State** – The condition of the Incoming Distribution CE is described by Enable, Disable, In-service, Out-of-service.
+
+##### 8.1.3.3.3 Actions
+
+The actions associated with a Incoming Distribution CE are those provided by management (e.g. Enable, Disable, Query).
+
+##### 8.1.3.3.4 Notifications
+
+The notifications associated with an Incoming Distribution CE are those provided by management (e.g. Enabled, Disabled, QueryResult).
+
+## 8.2 Communication Party
+
+### 8.2.1 Description and behaviour
+
+When a CP is specified by the computer it should at least identify the CE. However, the omission of a Call View should not make the CP ambiguous to the switch (i.e. preventing the switch from identifying a single relationship).
+
+When a CP is specified by the switch then both the Call View and the CE should be specified.
+
+### 8.2.2 Types
+
+**Line CP** – Maintains an abstract call view association between a Line CE and an Originating or Terminating Call View which is direction independent.
+
+**Distribution CP** – Maintains an abstract call view association between a Distribution CE and a Call View which is direction independent.
+
+### 8.2.3 Line CP
+
+#### 8.2.3.1 Description and behaviour
+
+A Line CP maintains an abstract call view association between a Line CE and a particular Call View which is direction independent. See Figure 6.
+
+![Diagram of a Switch containing OCV/TCV, Line CE, and Line CP components.](18722c46c9e8475524e634dedd08bac2_img.jpg)
+
+The diagram shows a rectangular box labeled 'Switch'. Inside the box, on the left, is a circle containing the text 'OCV' and 'TCV'. On the right is a rectangle labeled 'Line CE'. At the bottom center is a circle labeled 'Line CP'. A thick horizontal line passes through the center of the 'OCV/TCV' circle and the 'Line CE' rectangle. An arrow points from the 'Line CP' circle up to this thick horizontal line. Below the diagram, the text 'T1168070-94/d06' is present.
+
+Diagram of a Switch containing OCV/TCV, Line CE, and Line CP components.
+
+FIGURE 6/Q.1301
+
+##### Line CP
+
+#### 8.2.3.2 Attributes
+
+**Line CP Identifier** – Each Line CP has a unique identifier. A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**Call View Identifier** – Only one Call View Identifier may be associated with each Line CP.
+
+**Line CE** – Only one Line CE may be associated with each Line CP.
+
+**State** – The abstract state association between the Line CE and a Call View (Null, Active, Held).
+
+#### 8.2.3.3 Actions
+
+The actions associated with a Line CP are those provided by management (Enable, Disable, Query).
+
+#### 8.2.3.4 Notifications
+
+The notifications associated with a Line CP are those provided by management (Enabled, Disabled, QueryResult).
+
+### 8.2.4 Distribution CP
+
+#### 8.2.4.1 Description and behaviour
+
+Distribution CP maintains an abstract call view direction independent association between a Distribution CE and a Distribution Call View.
+
+#### 8.2.4.2 Types
+
+**Incoming Distribution CP** – An entity that maintains an abstract call view association between an Incoming Distribution CE and a Distribution Call which is direction independent.
+
+**Outgoing Distribution CP** – Not defined by this Recommendation.
+
+#### 8.2.4.3 Incoming Distribution CP
+
+##### 8.2.4.3.1 Description and behaviour
+
+Incoming Distribution CP maintains an abstract call view association between an Incoming Distribution CE and an Incoming Distribution Call View which is direction independent. See Figure 7.
+
+![Diagram of a Switch containing an Incoming Distribution CV, an Incoming Distribution CE, and an Incoming Distribution CP.](2de714cedbbdd36f901f71bafa78f75a_img.jpg)
+
+The diagram shows a rectangular box labeled 'Switch'. Inside the box, there are three components: 'Incoming Distribution CV' (represented by a circle on the left), 'Incoming Distribution CE' (represented by a rectangle on the right), and 'Incoming Distribution CP' (represented by a circle at the bottom). A thick horizontal line connects the 'Incoming Distribution CV' and the 'Incoming Distribution CE'. An arrow points from the 'Incoming Distribution CP' up to this thick horizontal line. Below the diagram, the text 'T1 168080-94/d07' is present.
+
+Diagram of a Switch containing an Incoming Distribution CV, an Incoming Distribution CE, and an Incoming Distribution CP.
+
+FIGURE 7/Q.1301  
+**Incoming Call Distribution CP**
+
+##### 8.2.4.3.2 Attributes
+
+**Incoming Distribution CP Identifier** – Each Incoming Distribution CP has a unique identifier. A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**Call View Identifier** – Only one Call View identifier may be associated with each Incoming Distribution CP.
+
+**Incoming Distribution CE** – Only one Incoming Distribution CE may be associated with each Incoming Distribution CP.
+
+**State** – The abstract state association between the incoming Distribution CE and an Incoming Distribution Call View (Null, Active, Held).
+
+##### 8.2.4.3.3 Actions
+
+The actions associated with an Incoming Call Distribution CP are those provided by management (Enable, Disable, Query).
+
+##### 8.2.4.3.4 Notifications
+
+The notifications associated with an Incoming Call Distribution CP are those provided by management (Enabled, Disabled, QueryResult).
+
+## 8.3 User
+
+### 8.3.1 Description and Behaviour
+
+An entity that makes direct use of a CE (e.g. initiates or answers a Call). A user may be associated with multiple CEs and Call Views. See Figure 8.
+
+![Diagram showing a Switch containing a Line CE connected to a User.](9b62a616c7a1097c5da57f001ab6dd64_img.jpg)
+
+The diagram illustrates a 'Switch' represented by a large rectangle. Inside this rectangle is a smaller rectangle labeled 'Line CE'. To the right of the 'Switch' rectangle is a rounded rectangle labeled 'User'. A thick black horizontal oval connects the 'Line CE' rectangle to the 'User' rounded rectangle. Below the diagram, the text 'T1168090-94/d08' is visible.
+
+Diagram showing a Switch containing a Line CE connected to a User.
+
+FIGURE 8/Q.1301
+
+User
+
+### 8.3.2 Types
+
+**Registered User** – A user that is identified by some log-on process.
+
+- **Agent** – A type of registered user that is distinguished from other users by being able to log-on to systems which distribute calls.
+- **Other Registered User** – A type of registered user that performs a registration or explicit identification action, e.g. authorization code.
+
+**Non-Registered User** – A user whose identity cannot be ascertained by TASC.
+
+### 8.3.3 Registered User
+
+#### 8.3.3.1 Description and behaviour
+
+A user that is identified by some log-on process.
+
+#### 8.3.3.2 Attributes
+
+**Registered User Identifier** – Each registered user has a unique identifier.
+
+**Call View Identifiers** – One or more Call View Identifiers may be associated a single each registered user.
+
+**Line CEs** – One or more Line CE Identifiers may be associated with a single registered user.
+
+**State** – The condition of the registered user at a Line CE (e.g. Null, Active).
+
+#### 8.3.3.3 Actions
+
+The actions associated with a User are those provided by management (Enable, Disable, Query).
+
+#### 8.3.3.4 Notifications
+
+The notifications associated with a User are those provided by management (Enabled, Disabled, QueryResult).
+
+#### 8.3.3.5 Agent
+
+##### 8.3.3.5.1 Description and behaviour
+
+A type of registered user that is distinguished from other users by being able to log-on to systems which distribute calls. Agents may be members of one or more pools of agents or agent groups. An example of a system which coordinates and distributes calls is an automatic call distribution system. The agent group can be identified by an agent group identifier. Agents are represented in TASC as agent objects. In subsequent text, the word agent means agent object.
+
+Agents have agent identifiers which uniquely identify the agent. Each agent may also have an agent password to be used during log-on for security.
+
+Agents may control their availability to receive calls by invoking agent operations such as log-on, log-off, and indicating ready or not ready to accept calls. Agents have states and agent operations result in state changes. The agent state may be used by the call distribution system to determine the availability of agents. An agent may or may not be in different states in different groups.
+
+Agent events may be reported by the switch to the computer when an agent invokes an operation at a telephone station or when an agent invokes one of the Manipulate Feature Functional Services (see Recommendation Q.1302).
+
+##### 8.3.3.5.2 Attributes
+
+**Agent Identifier** – Each Agent has a unique identifier.
+
+**Password** – Each Agent may have a unique password.
+
+**Agent Groups** – Agents may be members of one or more groups.
+
+**Call View Identifiers** – One or more Call View Identifiers may be associated with each Agent.
+
+**Line CE** – One or more Line CEs may be associated with each Agent.
+
+**State** – The condition of an Agent at a Line CE is described by Null, Agent-Logged-On, Agent-Logged-Off, Agent-Ready, Agent-Busy, Agent-Working-After-Call.
+
+##### 8.3.3.5.3 Actions
+
+The actions associated with an agent are those provided by management (Enable, Disable, Query) and those provided by agent action (Agent-Log-in, Agent-Log-Out, Agent-Ready, Agent-Busy, Agent-Working-After-Call).
+
+##### 8.3.3.5.4 Notifications
+
+The notifications associated with an agent are those provided by management (Enabled, Disabled QueryResult) and those provided by agent action (Logged-in, Logged-Out, Ready, Not-Ready, QueryResult).
+
+#### 8.3.3.6 Other registered user
+
+##### 8.3.3.6.1 Description and Behaviour
+
+A type of registered user that performs a registration or explicit identification action, e.g. authorization code. This user will have access to different services and those services may be limited by the registration process. For example, GVNS or CUG.
+
+##### 8.3.3.6.2 Attributes
+
+**Other Registered User Identifier** – Each Other Registered User has a unique identifier.
+
+**Password** – Each Other Registered User may have a unique password.
+
+**Other Registered User Groups** – Other Registered User may be members of one or more groups.
+
+**Call View Identifiers** – One or more Calls may be associated with an Other Registered User .
+
+**Line CE** – One or more Line CEs may be associated with an Other Registered User.
+
+**State** – The condition of the Other Registered User at a Line CE is described by (e.g. Null, Active).
+
+##### 8.3.3.6.3 Actions
+
+The actions associated with an Other Registered User are those provided by management (Enable, Disable, Query) and those provided by the Other Registered Users action (e.g. authorization code).
+
+##### 8.3.3.6.4 Notifications
+
+The notifications associated with an Other Registered User are those provided by management (Enabled, Disabled QueryResult) and those provided by Other Registered Users actions.
+
+### 8.3.4 Non-Registered User
+
+#### 8.3.4.1 Description and behaviour
+
+A user whose identity cannot be ascertained by TASC.
+
+#### 8.3.4.2 Attributes
+
+**Non-Registered User Identifier** – A non-registered user may be recognized by the Line CE Identifier with which the user is associated.
+
+**Call View Identifiers** – One or more Call View identifiers may be associated with each non-registered user.
+
+**Line CE** – One Line CE identifier may be associated with each non-registered user.
+
+**State** – The condition of the non-registered user at a Line CE (e.g. Null, Active, etc.).
+
+#### 8.3.4.3 Actions
+
+The actions associated with a Non-Registered User are those provided by management (Enable, Disable, Query).
+
+#### 8.3.4.4 Notifications
+
+The notifications associated with a Non-Registered User are those provided by management (Enabled, Disabled QueryResult).
+
+## 8.4 Call View
+
+There is a relationship among the CEs and Call Views. For a particular CE a particular Call View is presented. This Call View may present a unique set of events which is derived from the call related attributes of the CE. Each Call view presents a single-ended view of a call which is the view of call progress and call states from a switch's perspective for that particular CE.
+
+The call view for a Line CE is separated into originating and terminating Call Views.
+
+The following are the currently recognized Call Views.
+
+### 8.4.1 Originating Call View
+
+#### 8.4.1.1 Description and behaviour
+
+A type of Call View that has one CE originating the call and one CP.
+
+#### 8.4.1.2 Attributes
+
+**Call View Identifier** – Each Originating Call View has a unique identifier.
+
+**Line CE Identifier** – Each Originating Call View has one Line CE.
+
+**Line CP Identifier** – Uniquely identifies the relationship between one CE and one call view (originating). A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**Users** – Each Originating Call View has one User.
+
+**Call View State** – The condition of a Originating Call View.
+
+- 1) NULL
+- 2) PENDING
+- 3) ORIGINATING
+- 4) DELIVERED
+- 5) ESTABLISHED
+- 6) FAILED
+
+#### 8.4.1.3 Actions
+
+The actions associated with a call view are those provided by management (e.g. Query) and those actions initiated by application or user action (Make-Call, Answer-Call, Clear-Call, Hold-Call, Retrieve-Call, Transfer-Call, etc.).
+
+#### 8.4.1.4 Notifications
+
+The actions associated with a call view are those provided by management (e.g. QueryResult) and those actions as a result of application or user action (Service-Pending, Call-Delivered, Call- Established, Call-Cleared, etc.).
+
+### 8.4.2 Terminating Call View
+
+#### 8.4.2.1 Description and behaviour
+
+A type of Call that has one terminating CE and one CP.
+
+#### 8.4.2.2 Attributes
+
+**Call View identifier** – Each Terminating Call View has a unique identifier.
+
+**Line CE Identifier** – Each Terminating Call View has one Line CE.
+
+**Line CP Identifier** – Uniquely identifies the relationship between one CE and one call view (terminating). A CP identifier is comprised of a CE identifier, and CV identifier if required for unambiguous identification.
+
+**Users** – Each Terminating Call View has one User.
+
+**Call View State** – The condition of a Terminating Call View.
+
+- 1) NULL
+- 2) ARRIVED
+- 3) RECEIVED
+- 4) ESTABLISHED
+- 5) FAILED
+
+#### 8.4.2.3 Actions
+
+The actions associated with a call view are those provided by management (e.g. Query) and those actions initiated by an application or user action (Make-Call, Answer-Call, Clear-Call, Hold-Call, Retrieve-Call, Transfer-Call, etc.).
+
+#### 8.4.2.4 Notifications
+
+The actions associated with a call view are those provided by management (e.g. QueryResult) and those actions as a result of application or user action (Call Arrived, Call Received, Call Established, Call Cleared).
+
+### 8.4.3 Incoming Distribution Call View
+
+#### 8.4.3.1 Description and behaviour
+
+A type of Call View that may have one Incoming Distribution CE and one Incoming Distribution CP. An incoming Distribution Call View describes the behaviour when an incoming call arrives at and is manipulated by a distribution function within a switch.
+
+#### 8.4.3.2 Attributes
+
+**Call View Identifier** – Each Incoming Distribution Call view has a unique identifier.
+
+**Incoming Distribution CEs** – Each Incoming Distribution Call has at least one Line CE and may have two Line CEs.
+
+**Incoming Distribution CPs** – Each Incoming Distribution Call has at least one Incoming Distribution CP.
+
+**Incoming Distribution Call State** – The condition of an Incoming Distribution Call are the following states:
+
+- 1) NULL
+- 2) DISTRIBUTED
+- 3) FAILED
+
+#### 8.4.3.3 Actions
+
+The actions associated with an Incoming distribution call view are those provided by management (e.g. Query).
+
+#### 8.4.3.4 Notifications
+
+The actions associated with an Incoming distribution call view are those provided by management and state transitions (e.g. QueryResult).
+
+# 9 Call view states
+
+The call view states are an abstraction of the call processing activity in the switch that particularly relates to a CE. Not all call processing activities are reflected in the TASC call view. For example, during the PENDING state, the destination CE address information is collected, yet the collection of the digit is not reported to the computer.
+
+Call view state transitions are reflected by call progress events which are reported at the connection. These call progress events uniquely indicate the new call view state.
+
+The following template is used to describe the call states:
+
+**Description** – Describes the state.
+
+**Entry Event Reported** – Identifies the event reported for the state transition.
+
+## 9.1 Call View State descriptions
+
+### 9.1.1 Originating states
+
+Figure 9 shows the state transition diagram from the originating end perspective. The following originating states are defined:
+
+- 1) NULL
+- 2) PENDING
+- 3) ORIGINATED
+- 4) DELIVERED
+- 5) ESTABLISHED
+- 6) FAILED
+
+#### 9.1.1.1 NULL state
+
+##### Description
+
+The state where no call exists from the perspective of the TASC single-ended view. For example, the switch may verify the authorization of this CE to place an outgoing call with given properties (e.g. bearer capability or CE restrictions) before exiting the NULL state. The type of authorization may vary for different types of originating resources.
+
+**Entry Event Reported:** Call\_Cleared.
+
+#### 9.1.1.2 PENDING state
+
+##### Description
+
+The switch is collecting information for the purpose of processing the call. In addition, other information may be collected.
+
+**Entry Event Reported:** Service\_Pending.
+
+#### 9.1.1.3 ORIGINATED state
+
+##### Description
+
+Destination address analysis, route selection, and routing initiation are performed by the switch. Authorization may be performed.
+
+**Entry Event Reported:** Call\_Originated.
+
+#### 9.1.1.4 DELIVERED state
+
+##### Description
+
+The terminating end of the call is alerting.
+
+**Entry Event Reported:** Call\_Delivered.
+
+#### 9.1.1.5 ESTABLISHED state
+
+##### Description
+
+The destination CE has answered the call and the parties in the call may exchange information.
+
+**Entry Event Reported:** Call\_Established.
+
+#### 9.1.1.6 FAILED state
+
+##### Description
+
+Normal call progression has been aborted. Call failure indication is provided to calling party (e.g. busy).
+
+**Entry Event Reported:** Call\_Failed.
+
+![State transition diagram for originating call view states. States: NULL, PENDING, ORIGINATED, DELIVERED, ESTABLISHED, FAILED. Transitions include Call-Cleared, Service-Pending, Call-Originated, Call-Failed, Call-Delivered, Call-Established.](2119293733c74fc64de88aefd597f4bb_img.jpg)
+
+```
+stateDiagram-v2
+    [*] --> NULL
+    NULL --> PENDING: Service-Pending
+    PENDING --> NULL: Call-Cleared
+    PENDING --> ORIGINATED: Call-Originated
+    PENDING --> FAILED: Call-Failed
+    ORIGINATED --> NULL: Call-Cleared
+    ORIGINATED --> DELIVERED: Call-Delivered
+    ORIGINATED --> FAILED: Call-Failed
+    DELIVERED --> NULL: Call-Cleared
+    DELIVERED --> ESTABLISHED: Call-Established
+    DELIVERED --> FAILED: Call-Failed
+    ESTABLISHED --> NULL: Call-Cleared
+    ESTABLISHED --> PENDING: Call-Cleared
+    FAILED --> NULL: Call-Cleared
+    FAILED --> PENDING: Call-Failed
+```
+
+State transition diagram for originating call view states. States: NULL, PENDING, ORIGINATED, DELIVERED, ESTABLISHED, FAILED. Transitions include Call-Cleared, Service-Pending, Call-Originated, Call-Failed, Call-Delivered, Call-Established.
+
+T1168100-94/d09
+
+FIGURE 9/Q.1301  
+Originating call view states
+
+### 9.1.2 Terminating Call View States
+
+Figure 10 shows the state transition diagram from the terminating end perspective. The following terminating call view states are defined:
+
+- 1) NULL
+- 2) ARRIVED
+- 3) RECEIVED
+- 4) ESTABLISHED
+- 5) FAILED
+
+#### 9.1.2.1 NULL state
+
+##### Description
+
+The state where no call exists from the perspective of the TASC single-ended view. For example, the authorization to route an incoming call to the terminating CE may be performed (e.g. business group restrictions, restricted incoming access to a CE).
+
+**Entry Event Reported:** Call\_Cleared.
+
+#### 9.1.2.2 ARRIVED state
+
+##### Description
+
+A call has arrived at or within the switch and the destination CE (e.g. telephone set, etc.) has been identified. No validation has been done as to the suitability of the selected CE for termination of the call (i.e. the CE may be busy, out of service, restricted, etc.).
+
+**Entry Event Reported:** Call\_Arrived.
+
+#### 9.1.2.3 RECEIVED state
+
+##### Description
+
+The terminating end of the call is alerting.
+
+**Entry Event Reported:** Call\_Received.
+
+#### 9.1.2.4 ESTABLISHED state
+
+##### Description
+
+The two CEs are connected. Information may be exchanged between the two users participating in the call.
+
+**Entry Event Reported:** Call\_Established.
+
+#### 9.1.2.5 FAILED state
+
+##### Description
+
+Normal call progression has been aborted. Call failure indication is provided to calling party (e.g. busy).
+
+**Entry Event Reported:** Call\_Failed.
+
+![State transition diagram for Terminating call view states. States: NULL, ARRIVED, RECEIVED, ESTABLISHED, FAILED. Transitions: Call-Received (NULL to ARRIVED), Call-Arrived (NULL to ARRIVED), Call-Cleared (NULL to ARRIVED, NULL to RECEIVED, NULL to ESTABLISHED), Call-Failed (ARRIVED to FAILED), Call-Received (ARRIVED to RECEIVED), Call-Failed (RECEIVED to FAILED), Call-Established (RECEIVED to ESTABLISHED), Call-Established (ARRIVED to ESTABLISHED), Call-Cleared (FAILED to NULL).](7133ccf78043568ca62ecbcd43628a4a_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> NULL
+    NULL --> ARRIVED : Call-Received
+    NULL --> ARRIVED : Call-Arrived
+    NULL --> ARRIVED : Call-Cleared
+    NULL --> RECEIVED : Call-Cleared
+    NULL --> ESTABLISHED : Call-Cleared
+    ARRIVED --> FAILED : Call-Failed
+    ARRIVED --> RECEIVED : Call-Received
+    ARRIVED --> ESTABLISHED : Call-Established
+    RECEIVED --> FAILED : Call-Failed
+    RECEIVED --> ESTABLISHED : Call-Established
+    FAILED --> NULL : Call-Cleared
+  
+```
+
+T1168110-94/d10
+
+State transition diagram for Terminating call view states. States: NULL, ARRIVED, RECEIVED, ESTABLISHED, FAILED. Transitions: Call-Received (NULL to ARRIVED), Call-Arrived (NULL to ARRIVED), Call-Cleared (NULL to ARRIVED, NULL to RECEIVED, NULL to ESTABLISHED), Call-Failed (ARRIVED to FAILED), Call-Received (ARRIVED to RECEIVED), Call-Failed (RECEIVED to FAILED), Call-Established (RECEIVED to ESTABLISHED), Call-Established (ARRIVED to ESTABLISHED), Call-Cleared (FAILED to NULL).
+
+FIGURE 10/Q.1301  
+Terminating call view states
+
+### 9.1.3 Incoming Distribution Call View
+
+Figure 11 shows the state transition diagram from the incoming Distribution Call View perspective. The following distribution call view states are defined:
+
+- 1) NULL
+- 2) DISTRIBUTED ARRIVED
+- 3) FAILED
+
+#### 9.1.3.1 NULL
+
+##### Description
+
+The state where no call exists from the perspective of the TASC single-ended view.
+
+**Entry Event Reported:** Call\_Cleared (with a cause of distributed).
+
+#### 9.1.3.2 DISTRIBUTED ARRIVED
+
+##### Description
+
+A call has arrived at or within the switch and the destination CE (e.g. ACD, hunt group) has been identified. No validation has been done as to the suitability of the selected CE for termination of the call (i.e. the CE may be busy, out-of-service, restricted, etc.).
+
+**Entry Event Reported:** Call\_Arrived (with a cause of distributed).
+
+#### 9.1.3.3 FAILED
+
+##### Description
+
+Normal call progression has been aborted.
+
+**Entry Event Reported:** Call\_Failed (with a cause of distributed).
+
+![State diagram for Incoming Distribution Call View states showing transitions between NULL, DISTRIBUTION ARRIVED, and FAILED states.](58f4167687de8d7339594e5f6fbe0bc6_img.jpg)
+
+```
+stateDiagram-v2
+    [*] --> NULL
+    NULL --> DISTRIBUTION ARRIVED : Call-Arrived
+    DISTRIBUTION ARRIVED --> NULL : Call-Cleared
+    DISTRIBUTION ARRIVED --> FAILED : Call-Failed
+    FAILED --> NULL : Call-Cleared
+```
+
+The diagram illustrates the state transitions for the 'Incoming Distribution Call View'. It consists of three states: 'NULL', 'DISTRIBUTION ARRIVED', and 'FAILED'. Transitions are as follows: from 'NULL' to 'DISTRIBUTION ARRIVED' on 'Call-Arrived'; from 'DISTRIBUTION ARRIVED' to 'NULL' on 'Call-Cleared'; from 'DISTRIBUTION ARRIVED' to 'FAILED' on 'Call-Failed'; and from 'FAILED' to 'NULL' on 'Call-Cleared'. A small label 'T1168120-94/d11' is present near the bottom right of the diagram.
+
+State diagram for Incoming Distribution Call View states showing transitions between NULL, DISTRIBUTION ARRIVED, and FAILED states.
+
+FIGURE 11/Q.1301  
+Incoming Distribution Call View states
+
+#### 9.1.3.4 State diagrams
+
+### 9.1.4 Agent model
+
+The agent Model consists of the concepts of agent States and State Transitions.
+
+#### 9.1.4.1 Agent states
+
+The following states are defined for an agent:
+
+|                          |                                                                                                                                                                                                                                                                                     |
+|--------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| AGENT NULL               | The state where an Agent is not logged on to a CE. Logging-on to a CE causes a transition from this state and Logging-off from a CE causes a transition to this state.                                                                                                              |
+| AGENT NOT READY          | The state where an Agent is logged on to a CE but is not prepared to handle calls distributed by the distribution CE. An Agent may receive calls which are not handled by the distributor while in this state.                                                                      |
+| AGENT READY              | The state where an Agent is logged-on to a CE and is prepared and waiting to handle calls from the distribution function.                                                                                                                                                           |
+| AGENT BUSY               | The state where a CE, on behalf of an Agent, participates in a call.                                                                                                                                                                                                                |
+| AGENT WORKING AFTER CALL | The state where a CE, on behalf of an agent, inactively participates in a call. While in this state the agent cannot receive further calls from the distributor function but may well be performing administrative duties for a previous call, e.g. updating a business order form. |
+
+#### 9.1.4.2 Agent diagram and transitions
+
+Figure 12 shows the agent state model and agent state transitions.
+
+![State transition diagram for an agent with five states: AGENT NULL, AGENT NOT READY, AGENT READY, AGENT BUSY, and AGENT WORKING AFTER CALL. Transitions are shown as double-headed arrows between states.](a149b400127a3e3e50b3c98d27c5935c_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> NULL
+    NULL --> NOT_READY
+    NULL --> READY
+    NULL --> BUSY
+    NULL --> WORKING_AFTER_CALL
+    NOT_READY --> NULL
+    NOT_READY --> READY
+    NOT_READY --> BUSY
+    NOT_READY --> WORKING_AFTER_CALL
+    READY --> NULL
+    READY --> NOT_READY
+    READY --> BUSY
+    READY --> WORKING_AFTER_CALL
+    BUSY --> NULL
+    BUSY --> NOT_READY
+    BUSY --> READY
+    BUSY --> WORKING_AFTER_CALL
+    WORKING_AFTER_CALL --> NULL
+    WORKING_AFTER_CALL --> NOT_READY
+    WORKING_AFTER_CALL --> READY
+    WORKING_AFTER_CALL --> BUSY
+  
+```
+
+T1168130-94/d12
+
+State transition diagram for an agent with five states: AGENT NULL, AGENT NOT READY, AGENT READY, AGENT BUSY, and AGENT WORKING AFTER CALL. Transitions are shown as double-headed arrows between states.
+
+FIGURE 12/Q.1301
+
+Agent state model
+
+Agent state transitions are shown in the Table 1 below. The original state is shown in the far left-hand column and the state to which the agent is moving shown across the top. The valid events which will be reported are shown within the table body.
+
+TABLE 1/Q.1301
+
+Agent state transitions
+
+|                          | AGENT NULL       | AGENT NOT READY | AGENT READY | AGENT BUSY | AGENT WORKING AFTER CALL |
+|--------------------------|------------------|-----------------|-------------|------------|--------------------------|
+| AGENT NULL               |                  | Agent_logged_on |             |            |                          |
+| AGENT NOT READY          | Agent_logged_off |                 | Agent_ready |            |                          |
+| AGENT READY              | Agent_logged_off | Agent_not_ready |             | Agent_busy |                          |
+| AGENT BUSY               |                  | Agent_not_ready | Agent_ready |            | Agent_working_after_call |
+| AGENT WORKING AFTER CALL | Agent_logged_off | Agent_not_ready | Agent_ready |            |                          |
+
+The agent events are:
+
+- Agent\_Logged\_On
+- Agent\_Logged\_Off
+- Agent\_Not\_Ready
+- Agent\_Ready
+- Agent\_Busy
+- Agent\_Working\_After\_Call
+
+An agent will have access to both a data terminal for communicating to the application and a telephony terminal for communicating to the switch. An agent may perform operations at both of those terminals. If an agent logs on by using the telephony terminal, then the computer application will be informed of state changes by the events identified above. If an agent logs on by using the data terminal, then state changes will be notified to the switch by use of the Manipulate Agent Functional Service as defined within the TASC Functional Service definitions.

marked/Q/T-REC-Q.1704-200810-I_PDF-E/raw.md

@@ -0,0 +1,539 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**Q.1704**
+
+(10/2008)
+
+SERIES Q: SWITCHING AND SIGNALLING
+
+Signalling requirements and protocols for IMT-2000
+
+---
+
+**Functional network architecture for  
+IMT-Advanced**
+
+Recommendation ITU-T Q.1704
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking it, symbolizing global connectivity and telecommunications. The text "International Telecommunication Union" is written in blue to the right of the globe.
+
+ITU logo
+
+# ITU-T Q-SERIES RECOMMENDATIONS
+
+## SWITCHING AND SIGNALLING
+
+|                                                                                |                      |
+|--------------------------------------------------------------------------------|----------------------|
+| SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE                                 | Q.1-Q.3              |
+| INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING                             | Q.4-Q.59             |
+| FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN                       | Q.60-Q.99            |
+| CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS                                   | Q.100-Q.119          |
+| SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4, 5, 6, R1 AND R2                    | Q.120-Q.499          |
+| DIGITAL EXCHANGES                                                              | Q.500-Q.599          |
+| INTERWORKING OF SIGNALLING SYSTEMS                                             | Q.600-Q.699          |
+| SPECIFICATIONS OF SIGNALLING SYSTEM No. 7                                      | Q.700-Q.799          |
+| Q3 INTERFACE                                                                   | Q.800-Q.849          |
+| DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1                                     | Q.850-Q.999          |
+| PUBLIC LAND MOBILE NETWORK                                                     | Q.1000-Q.1099        |
+| INTERWORKING WITH SATELLITE MOBILE SYSTEMS                                     | Q.1100-Q.1199        |
+| INTELLIGENT NETWORK                                                            | Q.1200-Q.1699        |
+| <b>SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000</b>                      | <b>Q.1700-Q.1799</b> |
+| SPECIFICATIONS OF SIGNALLING RELATED TO BEARER INDEPENDENT CALL CONTROL (BICC) | Q.1900-Q.1999        |
+| BROADBAND ISDN                                                                 | Q.2000-Q.2999        |
+| SIGNALLING REQUIREMENTS AND PROTOCOLS FOR THE NGN                              | Q.3000-Q.3999        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## **Recommendation ITU-T Q.1704**
+
+# **Functional network architecture for IMT-Advanced**
+
+## **Summary**
+
+Recommendation ITU-T Q.1704 specifies a long-term high-level network architecture for IMT-Advanced specified in Recommendations ITU-T Q.1702, Q.1703 and ITU-R M.1645.
+
+## **Source**
+
+Recommendation ITU-T Q.1704 was approved on 14 October 2008 by ITU-T Study Group 19 (2005-2008) under Recommendation ITU-T A.8 procedure.
+
+## **Keywords**
+
+IMT-Advanced.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2009
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## CONTENTS
+
+|                                                                     | Page |
+|---------------------------------------------------------------------|------|
+| 1 Scope .....                                                       | 1    |
+| 2 References.....                                                   | 1    |
+| 3 Definitions .....                                                 | 2    |
+| 3.1 Terms defined elsewhere.....                                    | 2    |
+| 3.2 Terms defined in this Recommendation.....                       | 2    |
+| 4 Abbreviations and acronyms .....                                  | 2    |
+| 5 Conventions .....                                                 | 3    |
+| 6 Introduction .....                                                | 3    |
+| 7 General principles of the functional architecture.....            | 3    |
+| 8 Functional network architecture overview .....                    | 4    |
+| 8.1 NGN architecture overview.....                                  | 4    |
+| 8.2 IMT-Advanced architecture overview and NGN .....                | 4    |
+| 9 Generalized functional architecture and functional entities ..... | 4    |
+| 9.1 Network functions .....                                         | 4    |
+| 9.2 Network functional entities .....                               | 5    |
+
+
+
+## Recommendation ITU-T Q.1704
+
+## Functional network architecture for IMT-Advanced
+
+# 1 Scope
+
+The scope of this Recommendation is to provide a long-term high-level network architecture for IMT-Advanced<sup>1</sup> as specified by [ITU-T Q.1703], [ITU-T Q.1702], and [ITU-R M.1645].
+
+This Recommendation identifies network functions specific to IMT-Advanced and defines the corresponding network functional entities through functional models, which will form the basis for further designating reference points and developing information flows and functional entity actions.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- |                |                                                                                                                                                 |
+|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------|
+| [ITU-T M.3060] | Recommendation ITU-T M.3060/Y.2401 (2006), <i>Principles for the management of next generation networks</i> .                                   |
+| [ITU-T Q.1701] | Recommendation ITU-T Q.1701 (1999), <i>Framework for IMT-2000 networks</i> .                                                                    |
+| [ITU-T Q.1702] | Recommendation ITU-T Q.1702 (2002), <i>Long-term vision of network aspects for systems beyond IMT-2000</i> .                                    |
+| [ITU-T Q.1703] | Recommendation ITU-T Q.1703 (2004), <i>Service and network capabilities framework of network aspects for systems beyond IMT-2000</i> .          |
+| [ITU-T Y.2011] | Recommendation ITU-T Y.2011 (2004), <i>General principles and general reference model for Next Generation Networks</i> .                        |
+| [ITU-T Y.2012] | Recommendation ITU-T Y.2012 (2006), <i>Functional requirements and architecture of the NGN release 1</i> .                                      |
+| [ITU-R M.1645] | Recommendation ITU-R M.1645 (2003), <i>Framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000</i> . |
+
+---
+
+<sup>1</sup> The term "IMT-Advanced" is now used in place of "systems beyond IMT-2000" per ITU-R Resolution 56 (2007).
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 functional entity:** [ITU-T Y.2012] An entity that comprises an indivisible set of specific functions. Functional entities are logical concepts, while groupings of functional entities are used to describe practical, physical implementations.
+
+**3.1.2 functional architecture:** [ITU-T Y.2012] A set of functional entities and the reference points between them used to describe the structure of an NGN. These functional entities are separated by reference points, and thus, they define the distribution of functions.
+
+NOTE – The functional entities can be used to describe a set of reference configurations. These reference configurations identify which reference points are visible at the boundaries of equipment implementations and between administrative domains.
+
+**3.1.3 reference point:** [ITU-T Y.2012] A conceptual point at the conjunction of two non-overlapping functional entities that can be used to identify the type of information passing between these functional entities.
+
+NOTE – A reference point may correspond to one or more physical interfaces between pieces of equipment.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation does not define any new terms.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|          |                                              |
+|----------|----------------------------------------------|
+| 3GPP     | 3rd Generation Partnership Project           |
+| AAA      | Authentication, Authorization and Accounting |
+| AP       | Access Point                                 |
+| APR      | Anchor Point Router                          |
+| AR       | Access Router                                |
+| AS       | Application Server                           |
+| CSCF     | Call Session Control Function                |
+| FE       | Functional Entity                            |
+| G-MM-FE  | Global Mobility Management Functional Entity |
+| HSS      | Home Subscriber Server                       |
+| IMT-2000 | International Mobile Telecommunications-2000 |
+| IP       | Internet Protocol                            |
+| L2       | Layer 2                                      |
+| L3       | Layer 3                                      |
+| L-MM-FE  | Local Mobility Management Functional Entity  |
+| NGN      | Next Generation Network                      |
+| P-CSC-FE | Proxy Call Session Control Functional Entity |
+| PD-FE    | Policy Decision Functional Entity            |
+
+|          |                                                |
+|----------|------------------------------------------------|
+| QoS      | Quality of Service                             |
+| RACF     | Resource and Admission Control Function        |
+| RAM-FE   | Radio Access Management Functional Entity      |
+| RAN      | Radio Access Network                           |
+| SCF      | Service Control Function                       |
+| S-CSC-FE | Serving Call Session Control Functional Entity |
+| TRC-FE   | Transport Resource Control Functional Entity   |
+
+# 5 Conventions
+
+Functional entities in this Recommendation with the same name as in [ITU-T Y.2012] follow the general concept stated in [ITU-T Y.2012]; however the former is not always identical to the latter mainly because of possible additional functionalities derived as a consequence of addressing mobility. Convergence, in a precise sense, in terms of functional entities that appear in this Recommendation and in [ITU-T Y.2012] is for further study.
+
+# 6 Introduction
+
+In defining a vision for the future of mobile telecommunications, a number of layers of detail is required. The highest layer is an overall end-user service oriented perspective. This is provided in [ITU-T Q.1701] and [ITU-T Q.1702].
+
+[ITU-T Q.1703] provides the service and network capabilities and/or requirements framework, from the network aspect, for IMT-Advanced.
+
+The next level of detail is the definition of the high-level network architecture for IMT-Advanced, which includes the definition of functional entities and its relationships. This level is the objective of this Recommendation.
+
+It is expected that a future Recommendation will define how the information should flow among the functional entities in IMT-Advanced, according to the functional network architecture model adopted.
+
+# 7 General principles of the functional architecture
+
+The functional architecture incorporates the following general principles:
+
+- Network architecture based on IP technology
+
+Access networks, which provide a rich set of access mechanisms using various wired and wireless access technologies, terminate layer two link characteristics and provide IP-based connection to core networks. Core networks and application servers connected to them are IP based.
+
+- Modular construction using expandable components
+
+The subsystems themselves, such as access networks, core networks, and application servers; as well as the systems built based on them are hierarchical. In particular, core networks provide universal interfaces to different access networks and to all kinds of application servers.
+
+Accessibility to each subsystem is separately controlled based on each operator's policy; on the other hand in particular, paths that users can control to access application servers are prepared.
+
+- Open interfaces between various systems  
+Interoperation with homogeneous networks and with heterogeneous networks is facilitated with open interfaces in various levels of subsystems.
+
+# **8 Functional network architecture overview**
+
+The IMT-Advanced architecture should support multiple access networks, converged services in a converged network, enhanced security and protection, and total service accessibility, based on the services and network capabilities framework of network aspects defined in [ITU-T Q.1703] and aligned with the NGN architecture.
+
+## **8.1 NGN architecture overview**
+
+The NGN architecture is based on the general principles defined in [ITU-T Y.2011]. It is further detailed in [ITU-T Y.2012] for transport and service stratum functions and in [ITU-T M.3060] for management functions that apply to both transport and service strata.
+
+## **8.2 IMT-Advanced architecture overview and NGN**
+
+The IMT-Advanced architecture is based on the general principles defined in [ITU-T Y.2011]. It is not necessarily identical to the NGN architecture because of additional functions derived as a consequence of addressing mobility, recognizing that these two architectures are moving towards convergence.
+
+# **9 Generalized functional architecture and functional entities**
+
+This clause identifies network functions specific to IMT-Advanced and defines the corresponding network functional entities through functional models, which will form the basis for further designating reference points and developing information flows and functional entity actions.
+
+It is intended to link service and network capabilities defined in [ITU-T Q.1703] and specific to IMT-Advanced into functional entities defined in the NGN architecture, when possible.
+
+The IMT-Advanced architecture that encompasses these identified functional entities is to be understood as generalized, to allow for possible plural instantiations in more specific service or technology contexts.
+
+## **9.1 Network functions**
+
+### **9.1.1 Mobility management**
+
+The mobility management function manages mobility of terminals. In other words, it manages handover, location updating and paging for terminals. At handover and paging, the mobility management component sets routing information in entities of transport network. At location updating, the mobility management component tracks the paging area information of the terminal.
+
+Different mechanisms are applied based on the mobility management state of the terminal; i.e., location management and handover.
+
+#### **9.1.1.1 Location management**
+
+When the terminal is in idle state (i.e., it is not involved in an active session and/or radio resources for the terminal have been released), the network needs to track the location of the terminal by means of location update from the terminal. The network is able to reach the idle state terminal through the paging procedure.
+
+#### **9.1.1.2 Handover management**
+
+When the terminal is in active state (i.e., it is involved in an active session), the mobile terminal is required to be able to communicate whilst changing its point of attachment to the network due to its movement.
+
+### **9.1.2 QoS management**
+
+QoS management is meant to provide an end-to-end QoS which includes wireless and wired networks. In NGN environments, QoS management will be performed by the resource and admission control function (RACF). QoS will be based on users' preferences and/or applications. QoS management will be highly inter-related to the service control function (SCF), mobility managements and authentication, authorization and accounting (AAA).
+
+In order to efficiently meet diverse QoS requirements from the users/applications and achieve flexibility in developing QoS-enabled applications with no knowledge of the underlying transport technology and QoS mechanisms, RACF provides its QoS management service relative to a SCF in the service stratum, through which the users/applications can communicate with RACF entities to send QoS requirements, receive results and so forth.
+
+In order to provide an end-to-end QoS in the overall network interconnecting multiple access technologies and different operators' networks, RACF applies a distribution mechanism that distributes end-to-end QoS bearer specifications to each network and access system along the end-to-end path. Based on the information elements of the QoS specification, the RACF of each network and access system makes a local decision that is optimized for the local network domain.
+
+When RACF receives a QoS set up request from the SCF in the service stratum, it starts to set up QoS for the session. RACF asks mobility management to give the information for the route that a user's packet passes.
+
+Allowing differentiated QoS for different users will require the authentication and authorization of users for the requested levels of QoS, as well as accounting procedures, if the QoS is to be modified.
+
+### **9.1.3 Call session control function (CSCF)**
+
+The call session control function basically handles transactions for call/session setup, termination and forwarding to other call session control functional entities. It interacts with other network functions (mobility management, QoS management, security management, etc.) in order to support the call/session.
+
+The call session control function is realized by two functional entities, i.e., the proxy call session control functional entity (P-CSC-FE) and the serving call session control functional entity (S-CSC-FE). The P-CSC-FE acts like a proxy function to mobile terminals. The S-CSC-FE controls the call/session for the mobile terminals. It maintains a call/session state for management purposes.
+
+## **9.2 Network functional entities**
+
+### **9.2.1 Mobility management function**
+
+#### **9.2.1.1 Access router (AR)**
+
+The access router (AR) is an entity that connects a terminal to the network. This entity connects the terminal directly at the network layer.
+
+It manages the entries that contain the mapping of the terminal's network layer address to a port that connects to the corresponding AP that is associated with the terminal. Packets addressed to the terminal are forwarded by referring to the entries.
+
+It creates, updates, or deletes the entries when a RAM-FE notifies it of the AP selected by the RAM-FE.
+
+#### **9.2.1.2 Access point (AP)**
+
+The access point (AP) is an entity that connects terminals directly at the link layer to the network. It is connected to the AR.
+
+It does not terminate any network or upper layer protocol. It terminates the link layer protocol.
+
+#### **9.2.1.3 Terminal**
+
+The terminal is a device used by service subscribers to access the network.
+
+It is an entity that can connect directly to AP(s) at the link layer and to AR(s) at the network layer.
+
+It sends/receives the network control requests/responses to/from network control entities.
+
+It has two states, active and dormant, in conjunction with the routing information management in the mobility management entities.
+
+The active and dormant states are defined as follows:
+
+**Active:** The state in which the terminal is ready to send and receive packets. The transport network has the routing information of the terminal the L-MM-FE is currently serving.
+
+**Dormant:** The state where the terminal is not ready to send or receive packets. The transport network is not ready to route packets to its destination.
+
+#### **9.2.1.4 Anchor point router (APR)**
+
+The anchor point router (APR) is a router located in the L-MM-FE domain. There may be several APRs in an L-MM-FE domain.
+
+It will receive all packets on behalf of the terminals it is serving and forward them to the current address of the terminals through the ARs.
+
+This function has redundancy to avoid a single point of failure and achieve load balancing, regardless of whether or not it is distributed or centralized.
+
+Several APRs are located in the L-MM-FE domain. An APR is selected for each terminal.
+
+The APR is selected by the L-MM-FE. The selected APR is used while the terminal moves within the L-MM-FE domain.
+
+The area in which the APR does not change even if the terminal moves is defined as the APR domain.
+
+#### **9.2.1.5 Global mobility management functional entity (G-MM-FE)**
+
+The global mobility management functional entity (G-MM-FE) manages the global mobility for terminals. Global mobility is mobility between L-MM-FE domains. The G-MM-FE manages the addresses of terminals and L-MM-FE, where the terminal is located in the L-MM-FE domain. The G-MM-FE is not involved in local mobility management.
+
+It receives updated information from L-MM-FE when the L-MM-FE of a terminal changes. It stores the address of the L-MM-FE, which is used for routing information retrieval for the terminals.
+
+The G-MM-FE receives retrieval requests of routing information of a terminal from a router. The G-MM-FE forwards the request to the L-MM-FE that manages the routing information of the target terminal.
+
+It manages handover between L-MM-FE domains. It receives notifications of change of the L-MM-FE domain which is currently accessed to/from a terminal, and updates routing information for the terminal in routers, if needed. The notification comes from L-MM-FE.
+
+#### **9.2.1.6 Local mobility management functional entity (L-MM-FE)**
+
+The local mobility management functional entity (L-MM-FE) manages the local mobility for terminals. Local mobility is mobility within an L-MM-FE domain. The L-MM-FE domain is an area where the mobility related signals are controlled by the same L-MM-FE, even if the terminal moves. The FE is also involved in global mobility, which is mobility between L-MM-FE domains.
+
+The area of L-MM-FE domain is identical to that of APR domain. (Because one same APR is used while a terminal moves in the L-MM-FE domain.)
+
+It receives updated information from terminals when terminal changes paging area. It stores the paging area information, which is used for paging the terminals.
+
+The L-MM-FE receives a retrieval request from the AR and resolves the address of the G-MM-FE that manages the L-MM-FE domain of the target terminal currently located. The L-MM-FE may have the database for resolving the G-MM-FE from the address of target terminal.
+
+The L-MM-FE receives retrieval requests of routing information of a terminal from another L-MM-FE by way of the G-MM-FE. The request may trigger the paging for the terminal. From the paging, the L-MM-FE finds the routing information of the terminal, and sends the information directly to the L-MM-FE that requested the routing information of the terminal.
+
+When locating a particular terminal, the L-MM-FE can look for the appropriate RAM-FE or for multiple RAM-FEs whose addresses are in correspondence to the terminal, and request the RAM-FE or multiple RAM-FEs to page the terminal.
+
+The L-MM-FE manages the APRs and decides upon the appropriate APR when a terminal activates at paging or when initiating a communication.
+
+The L-MM-FE manages the inter-AR terminal handover within the L-MM-FE domain. It receives notifications of change of the AR that is currently connected to a terminal, and updates the routing information for the terminal in the APR and/or other routers, if needed. The notification may come from a RAM-FE or an AR.
+
+In case of intra-AR handovers, the RAM-FE only notifies the selected AP to the AR to which the terminal is connected and it does not notify any information to the L-MM-FE. Therefore, the L-MM-FE does not engage in intra-AR handover for terminals.
+
+The L-MM-FE manages addresses of terminals and RAM-FE.
+
+When the terminal moves from one L-MM-FE domain to another, the communication quality during handover and handover mechanisms should be equivalent to the case of inter-AR handover.
+
+The L-MM-FE has redundancy to avoid a single point of failure and achieve load balancing. There are several L-MM-FEs in a L-MM-FE domain.
+
+An L-MM-FE is selected when the terminal comes to a new L-MM-FE domain (i.e., active terminals perform handover from one domain to another and dormant terminals perform location registration to the new L-MM-FE domain).
+
+#### **9.2.1.7 Radio access management functional entity (RAM-FE)**
+
+The radio access management functional entity (RAM-FE) provides common interfaces to the L-MM-FE and the PD-FE.
+
+The RAM-FE receives the location update request from each radio system via control signalling in the radio systems. It sends the location update request with the addresses of terminals, the addresses of RAM-FE and location information of terminals to the L-MM-FEs via the common interface.
+
+The RAM-FE receives the paging request from the L-MM-FE and starts the paging procedure for each relevant radio system. The RAM-FE manages L3/L2 addresses of terminals and/or the addresses of radio systems. Even if the RAM-FE receives the control signal updating the location
+
+information from the RAN, the RAM-FE does not send the signalling to the L-MM-FE if that RAM-FE has already sent the same information to L-MM-FE. RAM-FEs can select the most appropriate radio system or the radio system's AP based on user's preference, QoS profile negotiated, and radio resource usage of the candidate APs when starting the paging procedure or handover, by performing (resource and QoS) coordination among the radio systems with the PD-FE.
+
+The RAM-FE can be accommodated in an AR or in multiple ARs.
+
+RAM-FE notifies the AP to the relevant entities as follows:
+
+When the RAM-FE selects the AP, the RAM-FE checks the AR that accommodates the selected AP. If the selected AP and the AP currently used are accommodated by the same AR, the RAM-FE notifies it to the AR.
+
+If the selected AP and the AP currently used are not accommodated in the same AR, the RAM-FE notifies the AR that accommodates the selected AP and notifies the new AR to PD-FE.
+
+![Figure 1 – Functional model for mobility management. The diagram shows a network architecture with two home networks, Home1 and Home2, and two visited networks, Visited1 and Visited2. Home1 contains G-MM-FE1, L-MM-FE1, RAM-FE1, AR1, and APR1. Home2 contains G-MM-FE2, L-MM-FE2, RAM-FE2, AR2, and APR2. Visited1 contains Terminal 1, AP1, and AR1. Visited2 contains Terminal 2, AP2, and AR2. A central C-plane U-plane connects the home networks. The diagram illustrates the functional model for mobility management, showing the interaction between various functional entities (FEs) and network elements (ARs, APs, Terminals) across different network domains.](a26e142d3df5bef41a84a9dd099d7825_img.jpg)
+
+Figure 1 – Functional model for mobility management. The diagram shows a network architecture with two home networks, Home1 and Home2, and two visited networks, Visited1 and Visited2. Home1 contains G-MM-FE1, L-MM-FE1, RAM-FE1, AR1, and APR1. Home2 contains G-MM-FE2, L-MM-FE2, RAM-FE2, AR2, and APR2. Visited1 contains Terminal 1, AP1, and AR1. Visited2 contains Terminal 2, AP2, and AR2. A central C-plane U-plane connects the home networks. The diagram illustrates the functional model for mobility management, showing the interaction between various functional entities (FEs) and network elements (ARs, APs, Terminals) across different network domains.
+
+**Figure 1 – Functional model for mobility management**
+
+### 9.2.2 QoS management function
+
+In the NGN environment, QoS management will be performed by resource and admission control functions (RACF). The RACF executes policy-based transport resource control upon request of the SCF, determines transport resource availability, makes admission decisions, and applies controls to transport functions for enforcing the policy decisions. The RACF consists of two types of resource and admission control functional entities: the PD-FE (policy decision functional entity) and the TRC-FE (transport resource control functional entity). This decomposition of PD-FE and TRC-FE enables the RACF to support a variety of accesses and core networks (e.g., fixed and mobile access networks).
+
+#### 9.2.2.1 Transport function
+
+The transport function executes QoS policies to the IP flows based on the end-to-end QoS specifications instructed by PD-FE. That is, it marks the QoS class for packets and allocates the bandwidth to the flow. These instructions are directly sent to each transport function by the PD-FE.
+
+If the transport function does not have enough bandwidth to receive the instruction from PD-FE, it notifies the PD-FE that it cannot guarantee the required QoS for the communication, and then the PD-FE denies the communication.
+
+#### 9.2.2.2 Policy decision functional entity (PD-FE)
+
+This function acts as an end-to-end QoS allocation function and coordination function. It is in charge of performing the negotiations with mobile terminals trying to access the network (by means of a call initiation or a handoff) or P-CSC-FE, and routers and access systems via RAM-FE to provide the resources according to the network service level policies. To identify the routers that the users' packet passes, the PD-FE inquires the user's address to mobility management functions. It is
+
+also in charge of instructing the transport function to execute QoS policies based on the result of the negotiation.
+
+If the IP flow for the user data transfer expands to another network domain, PD-FEs in different networks negotiate with each other for inter-QoS allocation.
+
+In inter-AR handover cases, the PD-FE is notified of the new AR by the RAM-FE. The PD-FE inquires the new user's address to mobility management and instructs QoS execution to transport functions.
+
+#### 9.2.2.3 Transport resource control functional entity (TRC-FE)
+
+This function deals with the diversity of underlying transport technologies and provides the resource-based admission control decision results to the PD-FE. The TRC-FE is service-independent and consists of transport technology-dependent resource control functions. The PD-FE requests the TRC-FE in the involved transport networks to detect and determine the requested QoS resources along the media flow path. The TRC-FE may collect and maintain the transport network topology and the transport resource status information, and authorize resource admission control of a transport network, based on network information.
+
+#### 9.2.2.4 Radio access management functional entity for QoS
+
+Radio access management functional entity (RAM-FE) for QoS supports an interworking function between IMT-Advanced and various access systems. It converts each access system QoS signalling to/from common QoS signalling. In this negotiation, it asks the access system (e.g., radio resource management in 3GPP RAN) to setup radio bearer based on the request from the PD-FE.
+
+![Figure 2 – Functional model for QoS management. The diagram shows a sequence of functional blocks from left to right: Mobile terminal, Access system, IMT-Advanced (containing RAM-FE, RACF, PD-FE, TRC-FE, and Transport function), IMT-Advanced (containing PD-FE, TRC-FE, and Transport function), Access system, and Correspondent terminal. Two types of connections are shown: thin lines for 'QoS signalling' and thick lines for 'User IP flows'. The Mobile terminal connects to the first Access system. The first Access system connects to the first IMT-Advanced block via both signalling and flow lines. Inside the first IMT-Advanced block, the RAM-FE connects to the RACF, which connects to the PD-FE. The PD-FE connects to the TRC-FE, which in turn connects to the Transport function. The PD-FE also connects to the second IMT-Advanced block. Inside the second IMT-Advanced block, the PD-FE connects to the TRC-FE, which connects to the Transport function. The second IMT-Advanced block connects to the second Access system. Finally, the second Access system connects to the Correspondent terminal via both signalling and flow lines.](bffdddb47fced140f8d17fdc2a29f592_img.jpg)
+
+Figure 2 – Functional model for QoS management. The diagram shows a sequence of functional blocks from left to right: Mobile terminal, Access system, IMT-Advanced (containing RAM-FE, RACF, PD-FE, TRC-FE, and Transport function), IMT-Advanced (containing PD-FE, TRC-FE, and Transport function), Access system, and Correspondent terminal. Two types of connections are shown: thin lines for 'QoS signalling' and thick lines for 'User IP flows'. The Mobile terminal connects to the first Access system. The first Access system connects to the first IMT-Advanced block via both signalling and flow lines. Inside the first IMT-Advanced block, the RAM-FE connects to the RACF, which connects to the PD-FE. The PD-FE connects to the TRC-FE, which in turn connects to the Transport function. The PD-FE also connects to the second IMT-Advanced block. Inside the second IMT-Advanced block, the PD-FE connects to the TRC-FE, which connects to the Transport function. The second IMT-Advanced block connects to the second Access system. Finally, the second Access system connects to the Correspondent terminal via both signalling and flow lines.
+
+Figure 2 – Functional model for QoS management
+
+### 9.2.3 Call session control function (CSCF)
+
+The call session control function basically handles transactions for call/session setup, termination and forwarding to other call session control functional entities. It interacts with other network functions (mobility management, QoS management, security management, etc.) in order to support the call/session.
+
+The call session control function is realized by two functional entities, i.e., the proxy call session control functional entity (P-CSC-FE) and the serving call session control functional entity (S-CSC-FE). The P-CSC-FE acts like a proxy function to mobile terminals. The S-CSC-FE controls the call/session for the mobile terminals. It maintains a call/session state for management purposes.
+
+#### 9.2.3.1 Proxy call session control functional entity (P-CSC-FE)
+
+The proxy call session control functional entity forwards call/sessions to the serving call session control functional entity from mobile terminals and vice versa. When the call/session control signalling cannot be sent to the correspondent node, the P-CSC-FE requests for mobility
+
+management to activate the terminal. When QoS is requested from the terminal, the P-CSC-FE directs QoS management to reserve the required resource.
+
+The P-CSC-FE controls the call/session for a given user. The call/session is initiated by a mobile terminal or the P-CSC-FE itself.
+
+The P-CSC-FE and the mobile terminal send and receive the call/session via the radio access management functional entity, which converts from access specific signalling to common network session signalling.
+
+The P-CSC-FE determines a change related to an active mobile terminal, and/or to the content that is being provided to that terminal and controls the changes.
+
+The P-CSC-FE holds the S-CSC-FE address, mobility management address and QoS management address for a given user.
+
+#### **9.2.3.2 Serving call session control functional entity (S-CSC-FE)**
+
+The serving call session control functional entity performs call/session control and service initiation for a given terminal.
+
+The session initiation may be authenticated and authorized by security management (e.g., HSS in 3GPP networks).
+
+When the S-CSC-FE receives call/session signals from the P-CSC-FE, it resolves the correspondent's S-CSC-FE address by inquiring mobility management, and then forwards the session signal to the correspondent's S-CSC-FE.
+
+The parties of the call/session may be identified by a string of alphabet letters, E.164 numbers or others. The S-CSC-FE may retrieve the address of the parties' mobile terminal with the identifier from directory manager.
+
+The S-CSC-FE collects the relevant data; static data (user profile, mobile terminal profile) from the global database (e.g., HSS in 3GPP systems) and dynamic data of mobile terminals (service processing status, etc.) from the mobile terminals.
+
+The S-CSC-FE may send a trigger to a media converter, when the mobile terminals in use change.
+
+The S-CSC-FE holds the P-CSC-FE address where the terminal is accommodated.
+
+#### **9.2.3.3 Global database for CSCF**
+
+Global database is a master database that manages the S-CSC-FE address of each mobile terminal. When an S-CSC-FE inquires a correspondent's S-CSC-FE address, it answers the correspondent S-CSC-FE address. When global database has no information of a mobile terminal, it returns null information, which means that the mobile terminal has not yet registered itself.
+
+#### **9.2.3.4 Radio access management functional entity for CSCF**
+
+Radio access management functional entity for the CSCF supports an interworking function between IMT-Advanced and various access systems. It converts each access system session signalling to/from common session signalling.
+
+##### **9.2.3.5 Application server (AS)**
+
+An application server (AS) offers value-added services. To this end, it interacts with the S-CSC-FE and global database. The application server may host and execute services with service logics.
+
+![Functional model for call session control function diagram showing two mobile terminals connected via access systems to a central IMT-Advanced network. The network contains AS, Global database, S-CSC-FE, and P-CSC-FE components, with RAM-FE units at the network edges.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+```
+
+graph LR
+    subgraph IMT-Advanced
+        AS1[AS] --- GD[Global database]
+        AS2[AS] --- GD
+        S1[S-CSC-FE] --- GD
+        S2[S-CSC-FE] --- GD
+        S1 --- S2
+        P1[P-CSC-FE] --- S1
+        P2[P-CSC-FE] --- S2
+        RAM1[RAM-FE] --- P1
+        P2 --- RAM2[RAM-FE]
+    end
+    MT1[Mobile terminal] --- AS1yst[Access system] --- RAM1
+    RAM2 --- AS2yst[Access system] --- MT2[Mobile terminal]
+  
+```
+
+Functional model for call session control function diagram showing two mobile terminals connected via access systems to a central IMT-Advanced network. The network contains AS, Global database, S-CSC-FE, and P-CSC-FE components, with RAM-FE units at the network edges.
+
+Q.1704(08)\_F03
+
+**Figure 3 – Functional model for call session control function**
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                             |
+|-----------------|---------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                           |
+| Series D        | General tariff principles                                                                   |
+| Series E        | Overall network operation, telephone service, service operation and human factors           |
+| Series F        | Non-telephone telecommunication services                                                    |
+| Series G        | Transmission systems and media, digital systems and networks                                |
+| Series H        | Audiovisual and multimedia systems                                                          |
+| Series I        | Integrated services digital network                                                         |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals |
+| Series K        | Protection against interference                                                             |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant     |
+| Series M        | Telecommunication management, including TMN and network maintenance                         |
+| Series N        | Maintenance: international sound programme and television transmission circuits             |
+| Series O        | Specifications of measuring equipment                                                       |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                |
+| <b>Series Q</b> | <b>Switching and signalling</b>                                                             |
+| Series R        | Telegraph transmission                                                                      |
+| Series S        | Telegraph services terminal equipment                                                       |
+| Series T        | Terminals for telematic services                                                            |
+| Series U        | Telegraph switching                                                                         |
+| Series V        | Data communication over the telephone network                                               |
+| Series X        | Data networks, open system communications and security                                      |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks   |
+| Series Z        | Languages and general software aspects for telecommunication systems                        |