Key telephone system

Details Key telephone system Key telephone system

1978-06-21

1980-11-18

Brigance, Gerald L.

179 99E, H04Q 518

Patent

active

042347653

ABSTRACT:
A key telephone system, in which a plurality of key telephone sets are selectively connected to a plurality of CO lines by the use of a plurality of talking lines under control of a key service unit and a plurality of control lines. In order to seize a CO line, a CO line seizure signal from one of key telephone sets is time-divisionally transmitted at a low speed and received by a speed change memory of the key service unit. A high-speed output from the speed change memory is added with dial or hook information and then space-divided for seizing a desired one of the CO lines. A talking operation, a holding operation, a privacy operation and a synchronizing operation in this system are performed on the base of the above operation principle.

REFERENCES:
patent: Re29078 (1976-12-01), Tate
patent: 3914559 (1975-10-01), Knollman
patent: 3935396 (1976-01-01), Barsellotti et al.
patent: 4027110 (1977-05-01), Takematsu et al.
patent: 4125749 (1978-11-01), Kinoshita et al.

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