152 lines
8.4 KiB
Plaintext
152 lines
8.4 KiB
Plaintext
Automatic Number Identification
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Automatic Number Identification (ANI) is nothing more than automatic means
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for immediately identifying the Directory Number of a calling subscriber. This
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process made it possible to utilize CAMA* (Centralized Automatic Message
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Accounting) systems in SxS, Panel, and Xbar #1 offices.
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The identity of the calling line is determined by ANI circuits installed
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in the types of CO's mentioned above. Xbar#5 offices have their own AMA
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(Automatic Message Accounting) equipment and utilize an AMA translator for
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automatically identifying the calling line.
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Before ANI was developed, each subscriber line (also called a local loop)
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had a mechanical marking device that kept track of toll charges. These devices
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were manually photographed at the end of the billing period and the amount of
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the subscribers bill was determined from that. This process was time
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consuming, so a new system (ANI) was developed.
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The major components of the ANI system used in SxS and Crossbar #1 are:
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Directory number network and bus arrangement* for connecting the sleeve (the
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lead that is added to the R(ing) and T(ip) wires of a cable pair at the MDF*
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(Main Distribution Frame));
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A lead of each line number through an identifier connector to the identifier
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circuit;
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Outpulser and Identifier connector circuit to seize an idle Identifier;
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Identifier circuit to ascertain the calling party's number and send it to the
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outpulser for subsequent transmission through the outpulser link to the ANI
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outgoing trunk;
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An ANI outgoing trunk to a Tandem office equipped with a CAMA system.
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The following is a synopsis of the ANI operations with respect to a toll
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call through a #1Xbar office. The call is handled in the normal manner by the
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CO equipment and is routed through an ANI outgoing trunk to a Tandem office.
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The identification process starts as soon as all digits of the called number
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are received by the CAMA sender in the Tandem office and when the district
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juncture in the Xbar office advances to its cut-through position (a position
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of the connecting circuits or paths between the line-link and trunk-link
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frames in the CO).
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Upon receiving the start identification signal from the CAMA equipment,
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the ANI outgoing trunk (OGT) establishes a connection through an outpulser
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link to an idle outpulser circuit. An idle identifier is then seized by the
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outpulser circuit through an internal Identifier connector unit. Then the
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identifier through the connector unit connects to the directory number network
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and bus system.
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At the same time, the identifier will signal the ANI trunk to apply a
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5800Hz identification tone to the sleeve lead of the ANI trunk. The tone is
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transmitted at a two-volt level over the S lead paths through the directory
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number network and bus system. It will be attenuated or decreased to the
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microvolt range by the time the identifier circuit is reached, necessitating
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a 120dB voltage amplification by the amplifier detector equipment in the
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identifier to insure proper digit identification and registration operations.
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A single ANI installation can serve as many as six CO's in a multi-office
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building. The identifier starts its search for the calling line number by
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testing or scanning successively the thousands secondary buses of each CO.
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When the 5800Hz signal is detected, the identifier grounds corresponding leads
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to the outpulser, to first register the digit of the calling office and then
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the thousands digit of the calling subscriber's number. The outpulser
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immediately translates the digit representing the calling office code into its
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own corresponding three digit office code. The identifier continues its
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scanning process successively on the groups of hundreds, tens, and units
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secondary buses in the calling office, and the identified digits of the
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calling number are also registered and translated in the outpulser's relay
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equipment for transmission to the tandem office. The outpulser is equipped
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with checking and timing features to promptly detect and record troubles
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encountered (This process may be responsible for some of the cards found while
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trashing). Upon completion of the scanning process, it releases the identifier
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and proceeds to outpulse in MF tones the complete calling subscriber's number
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to the CAMA equipment in the tandem office in the format of KP+X+PRE+SUFF+ST
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where the X is an information digit. The information digits are as follows:
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0-Automatic Identification (normal) 1-Operator Identification (ONI)*
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2-Identification Failure (ANIF)*
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(There is also other types of outpulsing of ANI information if the calling
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line has some sort of restriction on it).
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When all digits have been transmitted and the ANI trunk is cut-through for
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talking, the outpulser releases.
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In the tandem office, the calling party's number is recorded on tape in
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the CAMA equipment together with other data required for billing purposes.
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This information, including the time of when the called station answered and
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the time of disconnect, goes on AMA tapes.
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The tapes themselves are usually standard reel to reel magnetic tape, and are
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sent to the Revenue Accounting Office or RAO at the end of the billing period.
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So, to sum the entire ANI process up:
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The toll call is made. The CO routes the call through ANI trunks where an idle
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identifier is seized which then connects to the directory number network and
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bus system while signalling the ANI trunk to apply the needed 5800Hz tone to
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the Sleeve. The identifier begins a scanning process and determines the
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calling office number and the digits of the calling subscriber's number, which
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is sent by way of the outpulser in MF tones to the CAMA equipment in the
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tandem office. The call information is recorded onto AMA tapes and used to
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determine billing.
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Note that your number does show up on the AMA tape, if the circumstances
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are correct, (any toll call, whether it is from a message-rate line or from a
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flat-rate line). However, the AMA tapes do not record the calling line number
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in any separated format. They are recorded on a first-come, first-serve basis.
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Misc. Footnotes (denoted by an asterisk in the main article)
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---------------
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* ANIF-Automatic Number Identification Failure. This is when the ANI equipment
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does not work properly, and could occur due to a wide variety of
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technicalities. When ANIF occurs, something called ONI (Operator Number
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Identification) is used. The call is forwarded to a TSPS operator who requests
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the calling line number by saying something similar to 'What number are you
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calling from?'
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* CAMA-Centralized Automatic Message Accounting. CAMA is a system that records
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call details for billing purposes. CAMA is used from a centralized location,
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usually a Tandem office. CAMA is usually used to serve class 5 End Offices in
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a rural area near a large city which contains a Tandem or Toll Office. CAMA is
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similar to LAMA, except LAMA is localized in a specific CO and CAMA is not.
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* The Directory Number Network and bus system is a network involved with the
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ANI process. It is a grid of vertical and horizontal buses, grouped and
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classified as Primary or Secondary. There are 100 vertical and 100 horizontal
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buses in the Primary system. In the Secondary system, there are two sub-
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groups: Bus system #1 and Bus system #2, both of which have ten horizontal and
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vertical buses. These buses as a whole are linked to the Identifier in the ANI
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trunk and are responsible for identifying tens, hundreds, thousands and units
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digits of the calling number (After the Identifier begins its scanning
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process).
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* MDF-Main Distribution Frame. This is the area where all cable pairs of a
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certain office meet, and a third wire, the Sleeve wire, is added. The Sleeve
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wire is what is used in gathering ANI information, as well as determining a
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called lines status (off/on hook) in certain switching systems by presence of
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voltage. (voltage present on Sleeve, line is busy, no voltage, line is idle.)
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* ONI-Operator Number Identification. See ANIF footnote.
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NOTE: There are also other forms of Automatic Message Accounting, such as LAMA
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(Local Automatic Message Accounting). LAMA is used in the class 5 End Office
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as opposed to CAMA in a Toll Office. If your End Office had LAMA, then the ANI
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information would be recorded at the local level and sent from there. The LAMA
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arrangement may be computerized, in which it would denoted with a C included
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(LAMA-C or C-LAMA). |