Telephone operated signalling system

Patent

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Details

H04M 1102

Patent

active

040313220

ABSTRACT:
A telephone operated signalling system for use with a telephone having a manually operated switch and which is connected to a telephone substation where the system has room status indicating means responsive to operation of the manually operated switch, and means for disconnecting the telephone from the substation and connecting it to the signalling system. Indicator switch means are positioned between power means energizing the indicating means whereby the indicating means may be deenergized during long periods of time that the telephone is connected to the signalling system. A circuit is connected to the substation when the telephone is disconnected therefrom to provide means for preventing any malfunction signal caused by any test scanning current applied to the substation to indicate that the telephone is disconnected from the substation. Holding means are provided for holding the indicating means in a set position regardless of any power interruption in the signalling system.

REFERENCES:
patent: 3614325 (1971-10-01), Galian
patent: 3636280 (1972-01-01), Wetzel
patent: 3742141 (1973-06-01), Duncan
patent: 3777065 (1973-12-01), Galian
patent: 3854009 (1974-12-01), Pirnie
patent: 3892922 (1975-07-01), Stankus

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