Browse Prior Art Database

Calling Line Identifier Circuit

IP.com Disclosure Number: IPCOM000050619D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 59K

Publishing Venue

IBM

Related People

Chapman, RE: AUTHOR

Abstract

Circuitry is described that is useful in a telephone system for identifying a calling line. Existing systems identify one line at a time and cannot identify all calls during busy hours. This circuit allows multiple simultaneous identifications so that all calls are identified.

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Calling Line Identifier Circuit

Circuitry is described that is useful in a telephone system for identifying a calling line. Existing systems identify one line at a time and cannot identify all calls during busy hours. This circuit allows multiple simultaneous identifications so that all calls are identified.

The circuit counts the steps taken by the vertical and rotary magnets of a linefinder switch and passes the counts, along with a number which identifies the switch, to a computer, such as an IBM Series/1 computer. The computer then determines the calling directory number by comparing the inputs with a table. Each linefinder switch in the telephone office is equipped with one circuit. Therefore, the rate of call initiation has no effect on the ability of the system to identify subscribers. Furthermore, the information resides in the circuit for the duration of the call, giving the computer several minutes typically to find time to poll any given circuit. This system, when compared with existing installed systems, results in a significant improvement in the ability to identify calling subscribers in large offices.

Referring to the drawing, when a call is initiated, a step by step linefinder switch 1 steps to the calling subscriber's terminal (not shown) which is in a bank of 100 (10 by 10 array) terminals served by that switch. Switch 1 pulses its vertical magnet once for each vertical step until a ground mark indicates it has arrived at the row containing the subscriber's terminal. The pulses are conducted to a pulse shaper 2 which limits them to a voltage compatible with integrated circuit logic, and thence to a binary counter 3 which counts each pulse. After reaching the proper level, the linefinder pulses its rotary step magnet once for each rotary (horizontal) step until a ground mark indicates that it has found the subscriber's terminal. These pulses are conducted to a pulse shaper 4 and binary counter 5, as described above.

Later during the call...