Line circuit for key telephone systems

Details Line circuit for key telephone systems Line circuit for key telephone systems

1975-11-03

1977-12-20

Claffy, Kathleen H.

179 18FA, H04M 100

Patent

active

040643735

ABSTRACT:
A line circuit for providing line control between a central office or PBX line and the key telephone station subscriber instruments. The line circuit responds to ring currents to activate suitable signalling at stations having access to the called line. The circuit responds to a station going off-hook following ringing to provide the well-known responses. Call holding is also controlled by the line circuit. Within the circuit, the ring response is activated by a capacitor, the same capacitor being used to time out and terminate ring on a failure to respond and also to time the release of the circuit from the central office line.

REFERENCES:
patent: 3748401 (1973-07-01), Pesz
patent: 3748403 (1973-07-01), Schartmann et al.
patent: 3748404 (1973-07-01), Davis
patent: 3748405 (1973-07-01), Saba
patent: 3816670 (1974-06-01), Marshall

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