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+
+![ITU logo: a globe with the letters ITU and a lightning bolt symbol.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: a globe with the letters ITU and a lightning bolt symbol.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+## T.1
+
+**TERMINAL EQUIPMENT AND PROTOCOLS FOR  
+TELEMATIC SERVICES**
+
+---
+
+**STANDARDIZATION OF PHOTOTELEGRAPH  
+APPARATUS**
+
+**ITU-T Recommendation T.1**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation T.1 was published in Fascicle VII.3 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.
+
+## Recommendation T.1
+
+## STANDARDIZATION OF PHOTOTELEGRAPH APPARATUS
+
+*(former CCIT Recommendation D.1; amended at  
+New Delhi, 1960; Geneva, 1964; Mar del Plata, 1968;  
+Malaga-Torremolinos, 1984 and Melbourne, 1988)*
+
+The CCITT,
+
+*considering*
+
+that the transmission of pictures is possible only if certain characteristics of the transmitting and receiving equipments are identical,
+
+*unanimously declares the view*
+
+that phototelegraph apparatus and the associated modulating and demodulating equipment should be constructed and employed according to the following standards:
+
+### **1 Scanning track**
+
+At the transmitting apparatus the message area should be scanned in a “negative” direction. The orientation of the document in relation to the scanning plane will depend upon its dimensions and is of no consequence.
+
+At the receiving apparatus scanning takes place in a “negative” direction for “positive” reception and in a “positive” direction for “negative” reception.
+
+### **2 Index of cooperation**
+
+The normal index is 352 (corresponds to a factor of cooperation of 1105).
+
+The preferred alternative index, for use when less dense scanning is required, or when the characteristics of circuits (and particularly combined radio and metallic circuits) so demand, is 264 (a factor of cooperation of 829).
+
+The admissible tolerances on the above-mentioned values are  $\pm 1\%$ .
+
+### **3 Dimensions of apparatus**
+
+#### *3.1 Apparatus with drum scanning*
+
+The most currently used drum diameters are 66, 70 and 88 mm.
+
+The drum factor of the sending apparatus shall not be more than 2.4.
+
+The drum factor of the receiving apparatus shall not be less than 2.4.
+
+The width of the picture-retaining device (dead sector) may not exceed 15 mm. An allowance of 3% of the total length of a scanning line is also made for phasing. Thus, since the total circumference of a drum of the diameter of 66 mm is about 207 mm, the usable circumference will be at least 186 mm.
+
+### 3.2 Apparatus with flat-bed scanning
+
+The total lengths of the most current scanning lines are 207, 220 and 276 mm of which 15 mm are not used for effective transmission, because of the possibility that the receiving station may use a drum apparatus.
+
+Before transmitting a picture to a receiving station using a drum apparatus, it is necessary to ensure that the value of ratio:
+
+$$\frac{\text{length of document to be transmitted}^{1)} }{\text{total length of a scanning line}} \times \pi \text{Error! Bookmark not defined.}$$
+
+is less or at most equal to the drum factor of the receiver used.
+
+3.3 Table 1/T.1 gives corresponding values of index of cooperation  $M$ , factor of cooperation  $C$ , drum diameter  $D$ , total length of scanning line  $L$ , scanning pitch  $P$  and scanning density  $F$  for apparatus in most common use.
+
+TABLE 1/T.1
+
+| $M$ | $C$  | $D$ (mm) | $L$ (mm) | $P$ (mm) | $F$ (lines/mm) |
+|-----|------|----------|----------|----------|----------------|
+| 264 | 829  | 66       | 207      | 1/4      | 4              |
+| 264 | 829  | 70       | 220      | 1/3.77   | 3.77           |
+| 264 | 829  | 88       | 276      | 1/3      | 3              |
+| 350 | 1099 | 70       | 220      | 1/5      | 5              |
+| 352 | 1105 | 66       | 207      | 3/16     | 16/3           |
+| 352 | 1105 | 88       | 276      | 1/4      | 4              |
+
+*Note* – The maximum dimensions of the pictures to be transmitted result from the parameters given in the table.
+
+### 4 Reproduction ratio
+
+In the case where apparatus working with different lengths of scanning line (but with the same index of cooperation) are interconnected, there will be a slight change in size and the reproduction will bear the same proportion as the original, the ratio being that of the total lengths of the scanning lines.
+
+### 5 Drum rotation speed – scanning line frequency
+
+5.1 Table 2/T.1 gives the normal and approved alternative combinations of drum rotation speeds or of scanning line frequencies and indices of cooperation.
+
+<sup>1)</sup> Measured in the direction perpendicular to the scanning line.
+
+TABLE 2/T.1
+
+|                                                                                                 | Drum rotation speed<br>in rpm or scanning<br>line frequency | Index of cooperation |                                         |
+|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------|----------------------|-----------------------------------------|
+|                                                                                                 |                                                             | Metallic<br>circuits | Combined metallic<br>and radio circuits |
+| Normal conditions                                                                               | 60                                                          | 352                  | 352                                     |
+|                                                                                                 | 90                                                          |                      | 264                                     |
+| Alternatives for use when the<br>phototelegraph apparatus and metallic<br>circuits are suitable | 90                                                          | 264 and 352          |                                         |
+|                                                                                                 | 120                                                         | 264 and 352          |                                         |
+|                                                                                                 | 150                                                         | 264                  |                                         |
+
+*Note 1* – In the case of transmitters operating on metallic circuits, the index 264 is not intended to be used with an 88-mm drum. In the case of transmitters operating on combined metallic and radio circuits, the index 264 associated with a drum diameter of 88-mm is intended to be used only exceptionally.
+
+*Note 2* – The provisions given in the table are not intended to require the imposition of such standards on users who use their own equipment for the transmission of pictures over leased circuits. However, the characteristics of the apparatus used should be compatible with the characteristics of the circuits used.
+
+5.2 The speed of transmitters must be maintained as nearly as possible to the nominal speed and in any case within  $\pm 10$  parts in  $10^6$  of the nominal speed. The speed of receivers must be adjustable and the range of adjustment should be at least  $\pm 30$  parts in  $10^6$  from the nominal speed. After regulation, the speeds of the transmitting and receiving sets should not differ by more than 10 parts in  $10^6$ .
+
+### 6 Judder
+
+The stability of the speed during one rotation should be such that the maximum shift of the drum surface from the average position should not exceed one quarter of the scanning pitch  $P$  at normal index 352, which means that the maximum angle of the oscillations should not exceed 0.08 degree measured from the average position.
+
+### 7 Synchronization
+
+When phototelegraph stations have available a standard of frequency which is better than  $\pm 5$  parts in  $10^6$ , verification of the synchronism between the two stations may be dispensed with. In view of the saving of time, this method should be adopted wherever possible.
+
+To compare the speeds of a transmitter and a receiver, an alternating current whose frequency bears an unvarying relationship to the transmitter speed and has a nominal value of 1020 Hz is used.
+
+Where there is the possibility that the transmitter and receiver may be connected by a circuit liable to introduce frequency drifts, for example, by a carrier telephone circuit, the use of the simple 1020-Hz synchronizing tone is unsatisfactory. The preferred method of overcoming this difficulty is to transmit the phototelegraph carrier (of about 1900 Hz) modulated by the 1020-Hz synchronizing tone.
+
+At the receiving end, the 1020-Hz synchronizing frequency is restored by detection and can then be used in the normal manner.
+
+### 8 Phasing
+
+Phasing is performed after the speeds of the transmitter and receiver drums have been equalized.
+
+For phasing purposes, the transmitter sends a series of alternating white and black signals in such a way that the black lasts 95% and the white 5% of the total scanning line period (admissible tolerance:  $\pm 0.5\%$  of the total duration of a scanning line). The apparatus must be so adjusted that the pulses corresponding to the signal for white are transmitted:
+
+- during scanning of the “dead sector”, when drum apparatus is used,
+- during “lost time”, when flat-bed apparatus is used,
+
+and that they are placed at the middle of the dead sector (or of the interval corresponding to the lost time).
+
+(Tolerance admitted in the position of the "white" pulses:  $\Delta_E = \pm 1\%$  of a “total scanning line length”.)
+
+At the receiving station, phasing signals are used to start the apparatus so that short white pulses occur in the middle of the "lost time" (tolerance admitted:  $\Delta_R = \pm 2\%$  of a "total scanning line length").
+
+*Note* – These tolerances allow for the fact that the restitution of the original may deviate from its nominal position by 3% of a “total scanning line length”, when the sending and receiving stations are operating with the maximum authorized drift in the same direction.
+
+### 9 Contrast
+
+The transmitter must transmit the original document without changing the contrast of the tone scales of the picture to be transmitted.
+
+### 10 Modulation and demodulation equipment
+
+#### 10.1 Amplitude modulation
+
+Phototelegraph equipment shall normally provide for transmission and reception of an amplitude-modulated audio-frequency carrier, which is the normal mode of transmission for international metallic circuits.
+
+The level of the output signal of the transmitter shall be greatest for white and least for black. It is desirable that the ratio of nominal white signal to nominal black signal should be approximately 30 decibels.
+
+To simplify multi-destination operation and AM/FM conversion for radio operation it is desirable that the amplitude of the transmitted signal should vary linearly with the photocell voltage and that no corrections for tone scale should be made at the phototelegraph transmitting station.
+
+For audio-frequency telephone circuits, the frequency of the picture carrier-current is fixed at about 1300 Hz. This frequency gives the least delay distortion on lightly loaded underground cables.
+
+In the case of carrier telephone circuits providing a transmission band from 300 to 3400 Hz, a carrier-current frequency of about 1900 Hz is recommended.
+
+### 10.2 Frequency modulation
+
+Preferably phototelegraph apparatus should also provide for transmission and reception of a frequency-modulated audio-frequency carrier for use when necessary:
+
+- a) on combined metallic and radio circuits;
+- b) on wholly metallic circuits.
+
+In such a case, the characteristics of the frequency-modulated output should be:
+
+|                      |         |
+|----------------------|---------|
+| mean frequency.....  | 1900 Hz |
+| white frequency..... | 1500 Hz |
+| black frequency..... | 2300 Hz |
+
+The deviation of frequency should vary linearly with photocell voltage or, in the case of conversion from amplitude modulation to frequency modulation, with the amplitude of the amplitude-modulated carrier.
+
+The stability of the transmission must be such that the frequency corresponding to a given tone does not vary by more than 8 Hz in a period of 1 second and by more than 16 Hz in a period of 15 minutes.
+
+The receiving apparatus must be capable of operating correctly when the drift of black and white frequencies received does not exceed their nominal value by more than  $\pm 32$  Hz.
+
+*Note* - It is recognized that there are difficulties operating with these frequency limits on the public switched telephone network (PSTN) where certain types of signalling equipment are used. By prior agreement between users on the PSTN, alternative frequencies of 1300 Hz for white and 2100 Hz for black may be used.
+
+### **11 Positive or negative reception**
+
+Selection of positive or negative reception should be made by adjustment at the receiver. The adaptation of the transmitted signals to the characteristics of the photographic materials must also be effected at the receiving end according to the type of reproduction, negative or positive.
+
+### **12 Colour transmission (optional)**
+
+12.1 Phototelegraphy apparatus constructed in accordance with this Recommendation can be used in colour phototelegraphy by splitting the spectrum of light reflected from the picture elements into three basic colours and transmitting the three resulting signals sequentially. Then each signal can be treated and transmitted as a phototelegraphy signal as specified in this Recommendation above.
+
+12.2 The splitting of light reflected from picture element into three spectral components should be performed simultaneously. Thus synchro and phase coincidence and electronic colour correction can be achieved.
+
+12.3 The triad RGB (red, green, blue) shall be used as a basis of main colours. The red colour shall be in range of 575-700 nm, green 485-575 nm, blue 400-485 nm.
+
+*Note* – For the high quality reproduction of art images by means of graphic facilities, transmission of fourth components (i.e. black overtone) is desirable.
+
+12.4 The order of signal transmission shall be as follows: red, green, blue. In the case of negative reproduction the order of colour separated signals transmission is reversed.
+
+12.5 The speeds of the transmitting and receiving sets should not differ by more than 1 part in  $10^7$ .

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+
+
+![ITU logo: a globe with the letters ITU and a lightning bolt symbol.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: a globe with the letters ITU and a lightning bolt symbol.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**T.10**
+
+**TERMINAL EQUIPMENT AND PROTOCOLS FOR  
+TELEMATIC SERVICES**
+
+---
+
+**DOCUMENT FACSIMILE TRANSMISSIONS  
+ON LEASED TELEPHONE - TYPE CIRCUITS**
+
+**ITU-T Recommendation T.10**
+
+(Extract from the *Blue Book*)
+
+---
+
+## NOTES
+
+1 ITU-T Recommendation T.10 was published in Fascicle VII.3 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.
+
+## **Recommendation T.10**
+
+## **DOCUMENT FACSIMILE TRANSMISSIONS ON LEASED TELEPHONE-TYPE CIRCUITS**
+
+*(Geneva, 1964; amended at Mar del Plata, 1968;  
+at Geneva, 1972, 1976 and 1980)*
+
+## **1 Type of circuits to be used**
+
+The telephone-type circuits used should have characteristics as recommended in Recommendation H.12.
+
+*Note* – If the leased circuit is used alternately for telephone conversation and facsimile transmission and if the latter is unidirectional, it is not necessary to provide for disabling echo suppressors located on the long-distance leased circuit. However, when such a circuit is used for the simultaneous operation in both directions appropriate measures should be taken to disable echo suppressors before the actual facsimile transmission takes place.
+
+## **2 Modulation**
+
+Equipment conforming to Recommendation T.2 or Recommendation T.3 may be used. In the case of Recommendation T.2 equipment, either amplitude or frequency modulation may be chosen.
+
+## **3 Power**
+
+The maximum power output of the transmitting apparatus into the line shall not exceed 1 mW whatever the frequency.
+
+For frequency-modulation equipment conforming to Recommendation T.2, the level at the transmitter output shall be so adjusted that the level of the facsimile and control signals on the trunk circuit does not exceed –13 dBm0 regardless of the type of operation (duplex or simplex).
+
+For amplitude-modulation equipment conforming to Recommendation T.2, higher black levels may be used provided the mean power in any hour, in one direction of transmission, does not exceed 32 microwatts (–15 dBm0) at the zero relative level point of the trunk circuit.
+
+For equipment conforming to Recommendation T.3, higher white levels may be used provided the mean power in any hour, in one direction of transmission, does not exceed 32 microwatts (–15 dBm0) at the zero relative level point of the trunk circuit.
+
+## **4 Multipoint transmission**
+
+If facsimile transmissions take place simultaneously from a transmitting station to several receiving stations, arrangements shall be made at the junction points so that, on the circuits following the junction points, the same power levels are maintained as those prescribed for individual transmissions.
+
+## **5 Phase distortion**
+
+Equipment conforming to Recommendation T.2 should not require any special treatment. However, equipment conforming to Recommendation T.3 may require phase distortion correction in some cases.

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+
+
+![ITU logo: a globe with the letters ITU inside, and a lightning bolt symbol below it.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: a globe with the letters ITU inside, and a lightning bolt symbol below it.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+## T.102
+
+(03/93)
+
+**TELEMATIC SERVICES**
+
+**TERMINAL EQUIPMENTS AND PROTOCOLS  
+FOR TELEMATIC SERVICES**
+
+---
+
+**SYNTAX-BASED VIDEOTEX END-TO-END  
+PROTOCOLS FOR THE CIRCUIT MODE ISDN**
+
+**ITU-T Recommendation T.102**
+
+(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 T.102 was prepared by the ITU-T Study Group VIII (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
+
+|    |                                                             | <i>Page</i> |
+|----|-------------------------------------------------------------|-------------|
+| 1  | Scope .....                                                 | 1           |
+| 2  | Normative references .....                                  | 1           |
+| 3  | Definitions and abbreviations .....                         | 2           |
+|    | 3.1 Definitions .....                                       | 2           |
+|    | 3.2 Abbreviations .....                                     | 2           |
+| 4  | Overview .....                                              | 2           |
+| 5  | Configurations .....                                        | 2           |
+| 6  | General model .....                                         | 2           |
+|    | 6.1 Reference configuration .....                           | 3           |
+|    | 6.2 Protocol pillars .....                                  | 3           |
+| 7  | Service definition .....                                    | 3           |
+| 8  | Protocol .....                                              | 3           |
+| 9  | Coding .....                                                | 3           |
+| 10 | Use of CCITT Recommendation X.3 parameters .....            | 4           |
+| 11 | Layer 1 .....                                               | 4           |
+|    | 11.1 Basic access .....                                     | 4           |
+|    | 11.2 Primary rate access .....                              | 4           |
+| 12 | Layer 2 protocols .....                                     | 4           |
+|    | 12.1 Layer 2 protocol for the D-channel .....               | 4           |
+|    | 12.2 Layer 2 protocol for the B-channel .....               | 4           |
+| 13 | Layer 3 protocols .....                                     | 5           |
+|    | 13.1 Layer 3 protocol for the D-channel .....               | 5           |
+|    | 13.1.1 Terminal selection .....                             | 5           |
+|    | 13.1.2 Compatibility checking .....                         | 5           |
+|    | 13.1.3 Service specific use of supplementary services ..... | 5           |
+|    | 13.1.4 Call progress signals .....                          | 5           |
+|    | 13.2 Layer 3 protocol for the B-channel .....               | 5           |
+| 14 | Use of the Bearer Independent Service (BIS) .....           | 5           |
+|    | 14.1 Out-band procedure .....                               | 5           |
+|    | 14.1.1 Mapping of the BIS to Recommendation Q.931 .....     | 5           |
+|    | 14.1.1.1 BIS-N-CONNECT .....                                | 5           |
+|    | 14.1.1.2 BIS-N-DISCONNECT .....                             | 5           |
+|    | 14.2 In-band procedure .....                                | 5           |
+| 15 | Coordination between D- and B-channel .....                 | 6           |
+
+
+
+# SYNTAX-BASED VIDEOTEX END-TO-END PROTOCOLS FOR THE CIRCUIT MODE ISDN
+
+(Helsinki, 1993)
+
+# 1 Scope
+
+This Recommendation specifies the usage of all protocols and supplementary services up to and including layer 3 for syntax-based Videotex terminal equipment in the ISDN. The scope of this Recommendation is limited to circuit switched calls using the 64 kbit/s unrestricted digital information bearer capability and the DTE/DTE case of the network layer peer entities in B-channel connection.
+
+This standard is applicable to terminal equipment supporting the syntax-based Videotex using either basic access or primary rate access to the ISDN. In this context, a terminal equipment is either a Videotex terminal, a Videotex service centre, a Videotex access point or a Videotex host.
+
+This Recommendation is based on other CCITT Recommendations and International Standards and where necessary, it adds new or other requirements as application rules.
+
+# 2 Normative references
+
+This Recommendation incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references subsequent amendments to, or revisions of, any of these publications apply to this Recommendation only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies.
+
+- [0] CCITT Recommendation F.300 (1988), *Videotex Service*.
+- [1] CCITT Recommendation I.430 (1988), *Integrated Services Digital Network (ISDN) – Basic user-network interface, Layer 1 specification*.
+- [2] CCITT Recommendation I.431 (1988), *Integrated Services Digital Network (ISDN) – Primary rate user-network interface, Layer 1 specification*.
+- [3] CCITT Recommendation Q.921 (1990), *Integrated Services Digital Network (ISDN) – User-network interface data-link layer specification*.
+- [4] CCITT Recommendation Q.931 (1990), *Integrated Services Digital Network (ISDN) – User-network interface Layer 3, specification for basic call control*.
+- [5] CCITT Recommendation Q.932 [1988], *Generic Procedures for the Control of ISDN Supplementary Services*.
+- [6] CCITT Recommendation T.90 [1991], *Characteristics and Protocols for Terminals for Telematic Services in ISDN*.
+- [7] CCITT Recommendation T.105, *Syntax-based Videotex Application Layer Protocol*.
+- [8] CCITT Recommendation X.3, *Packet Assembly/Disassembly Facility (PAD) in a Public Data Network*.
+- [9] CCITT Recommendation X.75 (1984), *Packet-Switched Signalling System between Public Networks providing Data Transmission Services*.
+- [10] ISO/IEC 8208: 1990, *Information Technology – Data Communications – X.25 Packet Layer Protocol for Data Terminal Equipment*.
+- [11] ISO 7498, *Information processing systems – Open Systems Interconnection – Basic Reference Model*.
+
+# 3 Definitions and abbreviations
+
+## 3.1 Definitions
+
+For the purposes of this Recommendation, the following definitions apply:
+
+**data terminal equipment:** See ISO/IEC 8208 [10].
+
+**network connection:** See OSI Reference Model ISO 7498 [11].
+
+**network layer:** See OSI Reference Model ISO 7498 [11].
+
+**packet layer:** See ISO/IEC 8208 [10].
+
+**videotex access point:** See CCITT Recommendation F.300 [0].
+
+**videotex host:** This term describes a computer which offers one or more applications and/or facilities. It can be represented through a Videotex Host Computer, an External Videotex Host or a Videotex Service Centre.
+
+**videotex service centre:** See CCITT Recommendation F.300 [0].
+
+NOTE – According to CCITT Recommendation F.300 [0], a Videotex Service Centre provides host and/or access functions, i.e. it may also act as a Videotex Access Point.
+
+**videotex terminal:** See CCITT Recommendation F.300 [0]
+
+## 3.2 Abbreviations
+
+For the purpose of this Recommendation, the following abbreviations apply:
+
+|      |                                     |
+|------|-------------------------------------|
+| BIS  | Bearer Independent Service          |
+| CD   | Call Deflection                     |
+| DTE  | Data Terminal Equipment             |
+| ISDN | Integrated Services Digital Network |
+| HLC  | High Layer Compatibility            |
+| NSAP | Network Service Access Point        |
+| SBV  | Syntax-based Videotex               |
+| SUB  | Sub-addressing                      |
+| UUS  | User-to-User Signalling             |
+
+# 4 Overview
+
+Clause 4/T.105 [7] applies.
+
+The following subclauses specify the additional requirements to those as specified in Recommendation T.105 [7] to provide the Bearer Independent Service for syntax-based Videotex (SBV BIS).
+
+ISDN end-systems conforming to this Recommendation present protocol stacks at the S-or T-reference point as indicated in 6.2.
+
+# 5 Configurations
+
+Various configurations and topologies may be used, examples of which are given in informative Annex A/T.105 [7]. It shall be the responsibility of the Videotex Service providers to opt for the appropriate configuration(s) in the definition of the syntax-based Videotex Service.
+
+# 6 General model
+
+Clause 6/T.105 [7] applies with the additions given in 6.1 and 6.2.
+
+## 6.1 Reference configuration
+
+Figure 1 below illustrates the reference configuration for the DTE/DTE case of connection. The ISDN provides for an end-to-end circuit switched link between the terminal and the Videotex System.
+
+![Diagram of the reference configuration for the DTE/DTE case of connection. The diagram shows an ISDN SBVT (Syntax-based Videotex Terminal) connected to an ISDN network. The ISDN network is represented by a dashed circle containing two 'E T' (Exchange termination) blocks connected by a line with a cross in the middle. The ISDN SBVT is connected to the first 'E T' block via an 'S/T' (Coincident S- and T-reference point) interface. The second 'E T' block is connected to a 'Videotex System' via another 'S/T' interface. The reference point T0808480-91/d01 is indicated below the Videotex System.](a738993919a50143787084ee7ce6e2f2_img.jpg)
+
+S/T      Coincident S- and T-reference point  
+ET      Exchange termination  
+SBVT    Syntax-based Videotex Terminal
+
+T0808480-91/d01
+
+Diagram of the reference configuration for the DTE/DTE case of connection. The diagram shows an ISDN SBVT (Syntax-based Videotex Terminal) connected to an ISDN network. The ISDN network is represented by a dashed circle containing two 'E T' (Exchange termination) blocks connected by a line with a cross in the middle. The ISDN SBVT is connected to the first 'E T' block via an 'S/T' (Coincident S- and T-reference point) interface. The second 'E T' block is connected to a 'Videotex System' via another 'S/T' interface. The reference point T0808480-91/d01 is indicated below the Videotex System.
+
+FIGURE 1/T.102  
+Reference configuration
+
+## 6.2 Protocol pillars
+
+The protocol pillars are given in Figure 2.
+
+At layer 1, Recommendation I.430 [1] is used for ISDN basic access and Recommendation I.431 [2] is used for ISDN primary rate access.
+
+At layer 2, Recommendation Q.921 [3] provides for the LAPD data link procedures on the D-channel and Recommendation X.75 [9] provides for the LAPB data link procedures on the B-channel (additional application rules are given in clause 12).
+
+At layer 3, CCITT Recommendation Q.931 [4] signalling procedures are used on the D-channel, and ISO/IEC 8208 [10] packet level protocol is used in DTE/DTE operation on the B-channel (additional application rules are given in clause 13).
+
+The provision of the SBV BIS as defined in clause 11/T.105 [7] apply with regard to the mappings of the BIS primitives and parameters to and from the elements (additional rules are given in clause 14).
+
+# 7 Service definition
+
+Clause 7/T.105 [7] applies without any additional rule.
+
+# 8 Protocol
+
+Clause 8/T.105 [7] applies without any additional rule.
+
+# 9 Coding
+
+Clause 9/T.105 [7] applies without any additional rule.
+
+|   |                        |               |
+|---|------------------------|---------------|
+| 3 | Coordination (Note 1)  |               |
+|   | BIS (Note 2)           |               |
+|   | Q.931 [4]              | ISO 8208 [10] |
+| 2 | Q.921 [3]              | X.75 [9]      |
+| 1 | I.431 [2]<br>I.430 [1] |               |
+|   | Layer                  | B-channel     |
+
+# NOTES
+
+1 The coordination function specifies the relationship between D-channel and B-channel protocol pillars.
+
+2 The syntax-based Videotex Bearer Independent Service (SBV BIS) is defined in clause 11/T.105 [7]. It also covers some aspects of the out-band signalling procedures.
+
+FIGURE 2/T.102
+
+## Protocol pillars
+
+# 10 Use of CCITT Recommendation X.3 [8] parameters
+
+In addition to clause 10/T.105 [7], the “X.3 parameter reference number 11” is defined in this Recommendation and shall take the value 18 (64 kbit/s).
+
+# 11 Layer 1
+
+## 11.1 Basic access
+
+For terminals using the basic access to an ISDN, Recommendation I.430 [1] is applicable without any additional rule.
+
+## 11.2 Primary rate access
+
+For terminals using the primary rate access to an ISDN, Recommendation I.431 [2] is applicable without any additional rule.
+
+# 12 Layer 2 protocols
+
+## 12.1 Layer 2 protocol for the D-channel
+
+Subclause 2.2.2/T.90 [6] shall apply without any additional rule.
+
+## 12.2 Layer 2 protocol for the B-channel
+
+Subclause 2.2.3/T.90 [6] shall apply without any additional rule.
+
+# **13 Layer 3 protocols**
+
+## **13.1 Layer 3 protocol for the D-channel**
+
+### **13.1.1 Terminal selection**
+
+Subclause 2.2.4/T.90 [6] shall apply without any additional rule.
+
+### **13.1.2 Compatibility checking**
+
+Compatibility checking as part of the access protocol is specified in Annex B/Q.931 and shall apply without any additional rule.
+
+### **13.1.3 Service specific use of supplementary services**
+
+The procedures which are required for the use of supplementary services are specified in Recommendation Q.932 [5] and in I.240-Series and I.250-Series Recommendations.
+
+The use of supplementary services is optional.
+
+In order to realize some of the configurations mentioned in Annex A/T.105 [7], the following services may be necessary:
+
+- Sub-addressing (SUB);
+- User-to-User Signalling (UUS) Service 1;
+- Call Deflection (CD) in combination with UUS Service 1.
+
+### **13.1.4 Call progress signals**
+
+Call progress signals may be handled locally by the terminal.
+
+## **13.2 Layer 3 protocol for the B-channel**
+
+Subclause 2.2.5/T.90 [6] shall apply. Clause 4/T.90 [6] is also relevant, including the restrictions for Videotex. The use of NSAP does not apply.
+
+# **14 Use of the Bearer Independent Service (BIS)**
+
+## **14.1 Out-band procedure**
+
+The base Recommendation for the layer 3 protocol of the D-channel is Recommendation Q.931 [4] as already mentioned above. Clause 11/T.105 [7] defines the Bearer Independent Service (BIS) for syntax-based Videotex.
+
+General information about the out-band procedure of the BIS are described in subclause 11.3.1/T.105 [7] and the specific mapping is given below.
+
+### **14.1.1 Mapping of the BIS to Recommendation Q.931**
+
+#### **14.1.1.1 BIS-N-CONNECT**
+
+The protocol elements providing the BIS-N-CONNECT service are carried by the D-channel messages as defined in Table 1. Also the mapping of the parameters is given in Table 1.
+
+#### **14.1.1.2 BIS-N-DISCONNECT**
+
+The protocol elements providing the BIS-N-DISCONNECT service are carried by the D-channel messages as defined in Table 2. Also the mapping of the parameters is given in Table 2.
+
+## **14.2 In-band procedure**
+
+The service that the network layer entity provides to the Videotex application with respect to the establishment, release and data transfer of network connections, shall be as described in clause 11/T.105 [7].
+
+TABLE 1/T.102  
+**BIS-N-CONNECT mapping**
+
+| BIS                                                                                                  | D-channel                                             | Reference<br>Q.931               |
+|------------------------------------------------------------------------------------------------------|-------------------------------------------------------|----------------------------------|
+| Service primitives                                                                                   | Messages                                              |                                  |
+| BIS-N-CONNECT request<br>BIS-N-CONNECT indication<br>BIS-N-CONNECT response<br>BIS-N-CONNECT confirm | SETUP<br>SETUP<br>CONNECT<br>CONNECT                  | 3.2.9<br>3.2.9<br>3.2.3<br>3.2.3 |
+| Parameters                                                                                           | Information elements                                  |                                  |
+| Called Address                                                                                       | Called party number<br>Called party subaddress (Note) | 4.5.8<br>4.5.9                   |
+| Calling Address<br>Responding Address<br>BIS-user-data                                               | Not used<br>Not used<br>User-user                     | 4.5.29                           |
+| NOTE – The use of the subaddress is not mandatory and depends on local operation requirements.       |                                                       |                                  |
+
+TABLE 2/T.102  
+**BIS-N-DISCONNECT mapping**
+
+| BIS                                                          | D-channel                                                     | Reference<br>Q.931               |
+|--------------------------------------------------------------|---------------------------------------------------------------|----------------------------------|
+| Service primitives                                           | Messages                                                      |                                  |
+| BIS-N-DISCONNECT request<br>BIS-N-DISCONNECT indication      | DISCONNECT<br>DISCONNECT or<br>RELEASE or<br>RELEASE COMPLETE | 3.2.5<br>3.2.5<br>3.2.7<br>3.2.8 |
+| Parameters                                                   | Information elements                                          |                                  |
+| Originator and Reason<br>Responding Address<br>BIS-user-data | Cause<br>Not used<br>Not used                                 | 4.5.12                           |
+
+# 15 Coordination between D- and B-channel
+
+Clause 6/T.90 [6] shall apply without any additional rule.
+
+Annex A/T.105 [7] applies.
+
+Annex B/T.105 [7] applies.
+
+Annex C/T.105 [7] applies, with the following addition:
+
+- The default value for “X.3 parameter reference 11” is 18 [64 kbit/s].
+
+Annex D/T.105 [7] applies.
+
+Annex E/T.105 [7] applies.