Telephone security system
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Jul 12, 1983
Grant Date -
N/A
app pub date -
Aug 26, 1980
filing date -
Aug 26, 1980
priority date (Note) -
Expired
status (Latency Note)
Importance
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.
First Claim
Family
International Classification(s)
Cited Art Landscape
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