Telephone privacy circuit

Details Telephone privacy circuit Telephone privacy circuit

1984-04-03

1988-02-16

Dwyer, James L.

Telephonic communications

Diagnostic testing, malfunction indication, or electrical...

For detection of eavesdropping device

379387, 379396, H04M 168

Patent

active

047260483

ABSTRACT:
A telephone privacy circuit is disclosed. The privacy circuit preferably includes a voltage breakdown device which passes current only when the voltage across the device is greater than a predetermined value. The voltage breakdown device is connected in series with a telephone to be protected. The predetermined value is chosen to be lower than the line voltage across the tip and ring terminals of a telephone line when every telephone connected to that line is in the on-hook position. In one embodiment of the invention, the predetermined value is selected to be higher than the line voltage across the tip and ring terminals of the telephone line when a telephone connected to that line is placed on the off-hook condition. In another embodiment of the invention, a voltage breakdown device is connected to the gating element of an electronic latching device.

REFERENCES:
patent: 4136266 (1979-01-01), Cohen et al.
patent: 4459435 (1984-07-01), Foldvary et al.
patent: 4529843 (1985-07-01), Boeckmann

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