Call screening device

Details Call screening device Call screening device

1989-03-03

1990-06-26

Dwyer, James L.

Telephonic communications

Call or terminal access alarm or control

At substation

379188, H04M 166

Patent

active

049378546

ABSTRACT:
A call screening device is disclosed for use with a telephone system including one or more telephones connected to outside telephone service in order to screen incoming call signals directed to the telephone system and for providing, in response to a preselected security code signal, the incoming call signals to the telephones. The call screening device includes circuitry for storing the preselected security code signal and for receiving the incoming call signal and an incoming code signal from the outside telephone service. Circuitry is provided for comparing the incoming code signal with the preselected security code signal and for providing the call signal to one or more telephones when the comparing circuitry determines the incoming code signal corresponds to the preselected security code signal. The device may be activated or deactivated in response to a preselected control signal from any of the telephones. The device also includes circuitry for providing a ringing signal to each of the telephones during a period beginning with determination by the comparator circuitry that the incoming code signal received by the receiver circuitry corresponds to the preselected security code signal and ending with termination of the incoming call signal or answering of any one of the telephones, whichever occurs first.

REFERENCES:
patent: 4393278 (1983-07-01), Miyoshi
patent: 4674115 (1987-06-01), Kaleita et al.
patent: 4791664 (1988-12-01), Lutz et al.
patent: 4827501 (1989-05-01), Hansen

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