Signalling device for key telephone systems

Details Signalling device for key telephone systems Signalling device for key telephone systems

1975-04-18

1976-03-02

Claffy, Kathleen H.

179 84VF, 179 18AD, 179 37, H04M 150

Patent

active

039419444

ABSTRACT:
The present invention relates to a device which is to be used in conjunction with key telephone systems, as for example intercom systems. More particularly, the invention consists of a device for decoding the tone output from touch-tone telephones, indicating which digit has been operated and selectively signalling the called party. Special features include a minimum latching time for received signals and a time-out circuit. A relay decoding matrix is also covered with provision for accommodating either single or two digit codes. The device may be used in key telephone systems which include rotary dial equipment as well as touch-tone.

REFERENCES:
patent: 3582562 (1971-06-01), Sellari
patent: 3622710 (1971-11-01), Tothill
patent: 3701854 (1972-10-01), Anderson et al.
patent: 3780230 (1973-12-01), Bowen et al.
patent: 3806664 (1974-04-01), Bowen et al.
patent: 3875347 (1975-04-01), Alaily

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