Abbreviated dialing system

Details Abbreviated dialing system Abbreviated dialing system

1978-04-27

1979-10-16

Cooper, William C.

179 90B, H04M 344

Patent

active

041714695

ABSTRACT:
An abbreviated dialing system is connected in series with a telephone line connecting one or more subscriber telephone instruments to the telephone central office. This system incorporates either a low pass or other filter which prevents the transmission of Touch Tone signals from any subscriber telephone instrument to the telephone central office, but has negligible effect on the D.C. voltage, ring signal or dial tone signal sent out over the telephone line from the central office to the subscriber telephone equipment. A filter control circuit is controlled by logic circuitry to selectively either bypass the filter or insert it in series with the telephone line. When the subscriber lifts the handset of a telephone instrument, the filter is inserted in series with the telephone line. The subscriber then transmits an abbreviated series of Touch Tone signals which are intercepted and decoded by the system's logic circuitry. A decoded Touch Tone signal is generated and transmitted by the system to the central office which rings the telephone designated by the full sequence Touch Tone signal. Upon completion of this transmission, the filter control circuitry switches the filter out of the circuit to permit normal operation of the telephone system. In this manner a plurality of subscriber telephone instruments can access and control a single abbreviated dialing system. No modification of any of the existing subscriber telephone instruments or premises wiring is necessary.

REFERENCES:
patent: 3334190 (1967-08-01), Jenkins et al.
patent: 3993877 (1976-11-01), Sendyk et al.

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