Security system for cordless extension telephones

Details Security system for cordless extension telephones Security system for cordless extension telephones

1983-10-04

1987-03-31

Cangialosi, Salvatore

Telephonic communications

Audio message storage, retrieval, or synthesis

380 23, H04M 170

Patent

active

046544810

ABSTRACT:
In a cordless extension telephone system in which a base station is connected to telephone lines and communicates with a remote station by radio transmission, the base station in response to the presence of a ring signal on the telephone lines repeatedly transmits an eleven bit code at a predetermined bit rate. The remote station upon receiving the eleven bit code at least three times in succession generates an audio signal to indicate the presence of a incoming call. The user at the remote station may actuate a control to an "on" position or an "off" position. The remote station responds to the actuation of the control and will repeatedly transmit the eleven bit code plus one additional bit having a state indicating whether the control is actuated to the "on" state or the "off" state. The base station in response to receiving the eleven bit code at least three times in succession will enble or disable an isolation circuit in accordance with the twelfth bit of the code. The isolation circuit when enabled, will apply the signal on the telephone lines to the input of the transmitter of the base station and the output of the receiver of the base station to the telephone lines.

REFERENCES:
patent: 4039760 (1977-08-01), Gregory et al.
patent: 4053717 (1977-10-01), Snider
patent: 4119800 (1978-10-01), Girardi
patent: 4291197 (1981-09-01), Yonaga
patent: 4332981 (1982-06-01), Palombi et al.
patent: 4369443 (1983-01-01), Giallanza et al.
patent: 4436957 (1984-03-01), Mazza et al.
patent: 4467140 (1984-08-01), Fathauer et al.
patent: 4469918 (1984-09-01), Cripps

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