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Written by Doom Prophet and Phantom Phreaker |
Automatic Number Identification (ANI) is nothing more than automatic means |
for immediately identifying the Directory Number of a calling subscriber. This |
process made it possible to utilize CAMA* (Centralized Automatic Message |
Accounting) systems in SxS, Panel, and Xbar #1 offices. |
The identity of the calling line is determined by ANI circuits installed |
in the types of CO's mentioned above. Xbar#5 offices have their own AMA |
(Automatic Message Accounting) equipment and utilize an AMA translator for |
automatically identifying the calling line. |
Before ANI was developed, each subscriber line (also called a local loop) |
had a mechanical marking device that kept track of toll charges. These devices |
were manually photographed at the end of the billing period and the amount of |
the subscribers bill was determined from that. This process was time |
consuming, so a new system (ANI) was developed. |
The major components of the ANI system used in SxS and Crossbar #1 are: |
Directory number network and bus arrangement* for connecting the sleeve(the |
lead that is added to the R(ing) and T(ip) wires of a cable pair at the MDF* |
(Main Distribution Frame)); |
A lead of each line number through an identifier connector to the identifier |
circuit; |
Outpulser and Identifier connector circuit to seize an idle Identifier; |
Identifier circuit to ascertain the calling party's number and send it to the |
outpulser for subsequent transmission through the outpulser link to the ANI |
outgoing trunk; |
An ANI outgoing trunk to a Tandem office equipped with a CAMA system. |
The following is a synopsis of the ANI operations with respect to a toll |
call through a #1Xbar office. The call is handled in the normal manner by the |
CO equipment and is routed through an ANI outgoing trunk to a Tandem office. |
The identification process starts as soon as all digits of the called number |
are received by the CAMA sender in the Tandem office and when the district |
junctor in the Xbar office advances to its cut-through position (a position of |
the connecting circuits or paths between the line-link and trunk-link frames |
in the CO). |
Upon receiving the start identification signal from the CAMA equipment, |
the ANI outgoing trunk (OGT) establishes a connection through an outpulser |
link to an idle outpulser circuit. An idle identifier is then seized by the |
outpulser circuit through an internal Identifier connector unit. Then the |
identifier through the connector unit connects to the directory number network |
and bus system. |
At the same time, the identifier will signal the ANI trunk to apply a |
5800Hz identification tone to the sleeve lead of the ANI trunk. The tone is |
transmitted at a two-volt level over the S lead paths through the directory |
number network and bus system. It will be attenuated or decreased to the |
microvolt range by the time the identifier circuit is reached, necessitating |
a 120dB voltage amplification by the amplifier detector equipment in the |
identifier to insure proper digit identification and registration operations. |
A single ANI installation can serve as many as six CO's in a multi-office |
building. The identifier starts its search for the calling line number by |
testing or scanning successively the thousands secondary buses of each CO. |
When the 5800Hz signal is detected, the identifier grounds corresponding leads |
to the outpulser, to first register the digit of the calling office and then |
the thousands digit of the calling subscriber's number. The outpulser |
immediately translates the digit representing the calling office code into its |
own corresponding three digit office code. The identifier continues its |
scanning process successively on the groups of hundreds, tens, and units |
secondary buses in the calling office, and the identified digits of the |
calling number are also registered and translated in the outpulser's relay |
equipment for transmission to the tandem office. |
The outpulser is equipped with checking and timing features to promptly detect |
and record troubles encountered (This process may be responsible for some of |
the cards found while trashing). Upon completion of the scanning process, it |
releases the identifier and proceeds to outpulse in MF tones the complete |
calling subscriber's number to the CAMA equipment in the tandem office in the |
format of KP+X+PRE+SUFF+ST where the X is an information digit. The |
information digits are as follows: |
0-Automatic Identification (normal) 1-Operator Identification (ONI)* |
2-Identification Failure (ANIF)* |
(There is also other types of outpulsing of ANI information if the calling |
line has some sort of restriction on it). |
When all digits have been transmitted and the ANI trunk is cut-through for |
talking, the outpulser releases. |
In the tandem office, the calling party's number is recorded on tape in |
the CAMA equipment together with other data required for billing purposes. |
This information, including the time of when the called station answered and |
the time of disconnect, goes on AMA tapes. |
The tapes themselves are usually standard reel to reel magnetic tape, and are |
sent to the Revenue Accounting Office or RAO at the end of the billing period. |
So, to sum the entire ANI process up: |
The toll call is made. The CO routes the call through ANI trunks where an idle |
identifier is seized which then connects to the directory number network and |
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