==Phrack Inc.==



                    Volume Two, Issue Ten, Phile #7 of 9



                      Automatic Number Idenfification





                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

bus system while signalling the ANI trunk to apply the needed 5800Hz tone to

the Sleeve. The identifier begins a scanning process and determines the

calling office number and the digits of the calling subscriber's number, which

is sent by way of the outpulser in MF tones to the CAMA equipment in the

tandem office. The call information is recorded onto AMA tapes and used to

determine billing.



   Note that your number does show up on the AMA tape, if the circumstances

are correct, (any toll call, whether it is from a message-rate line or from a

flat-rate line). However, the AMA tapes do not record the calling line number

in any separated format. They are recorded on a first-come, first-serve basis.





Misc. Footnotes (denoted by an asterisk in the main article)

---------------



* ANIF-Automatic Number Identification Failure. This is when the ANI equipment

does not work properly, and could occur due to a wide variety of technical-

ities. When ANIF occurs, something called ONI (Operator Number Identification)

is used. The call is forwarded to a TSPS operator who requests the calling

line number by saying something similar to 'What number are you calling from?'



* CAMA-Centralized Automatic Message Accounting. CAMA is a system that records

call details for billing purposes. CAMA is used from a centralized location,

usually a Tandem office. CAMA is usually used to serve class 5 End Offices in

a rural area near a large city which contains a Tandem or Toll Office. CAMA is

similar to LAMA, except LAMA is localized in a specific CO and CAMA is not.



* The Directory Number Network and bus system is a network involved with the

ANI process. It is a grid of vertical and horizontal buses, grouped and class-

ified as Primary or Secondary. There are 100 vertical and 100 horizontal buses

in the Primary system. In the Secondary system, there are two sub-groups:Bus

system #1 and Bus system #2, both of which have ten horizontal and vertical

buses. These buses as a whole are linked to the Identifier in the ANI trunk

and are responsible for identifying tens, hundreds, thousands and units digits

of the calling number (After the Identifier begins its scanning process).



* MDF-Main Distribution Frame. This is the area where all cable pairs of a

certain office meet, and a third wire, the Sleeve wire, is added. The Sleeve

wire is what is used in gathering ANI information, as well as determining a

called lines status (off/on hook) in certain switching systems by presence of

voltage. (voltage present on Sleeve, line is busy, no voltage, line is idle.)



* ONI-Operator Number Identification. See ANIF footnote.



NOTE: There are also other forms of Automatic Message Accounting, such as LAMA

(Local Automatic Message Accounting). LAMA is used in the class 5 End Office

as opposed to CAMA in a Toll Office. If your End Office had LAMA, then the ANI

information would be recorded at the local level and sent from there. The LAMA

arrangement may be computerized, in which it would denoted with a C included

(LAMA-C or C-LAMA).





References and acknowledgements

-------------------------------

Basic Telephone Switching Systems (Second Edition) by David Talley

Understanding Telephone Electronics by Radio Shack/Texas Instruments



Other sysops are allowed to use this file on their systems as long as none of

it is altered in any way.



-End of file-

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