Security system with backup dialer
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Aug 3, 1993
Grant Date -
N/A
app pub date -
Jan 11, 1991
filing date -
Jan 11, 1991
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A security apparatus having two control and communications units adapted to monitor a system and to establish communications over a connected telephone line and to transmit an alarm upon the occurance of a predetermined event in the system. The first control and communications unit produces a characteristic signal when it is operational; and the second control and communications unit is adapted to monitor the characteristic signal produced by the first control and communications unit and to establish communications over the connected telephone line and transmit an alarm upon interruption of the characteristic signal. The characteristic signal is preferably a tone of predetermined frequency.
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Family
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Cited Art Landscape
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