Telephone security system

Details Telephone security system Telephone security system

1980-08-26

1983-07-12

Popek, Joseph A.

179 2A, H04M 338

Patent

active

043932789

ABSTRACT:
A unit is interposed between a telephone outlet and the set to answer a call and to respond to absence or presence of a subsequently dialed-in security code. Only when that code is dialed will the call be completed by effecting a through connection and causing the set to ring. This private unlisting automatically restricts accepting of calls only from callers to whom the code was given.

REFERENCES:
patent: 3654396 (1972-04-01), Biezeveld
patent: 3784721 (1974-01-01), Kilby
patent: 3829616 (1974-08-01), Blouch
patent: 4006316 (1977-02-01), Bolgiano

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