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Security system with backup dialer

  • US 5,233,640 A
  • Filed: 01/11/1991
  • Issued: 08/03/1993
  • Est. Priority Date: 01/11/1991
  • Status: Expired due to Term
First Claim
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1. Security apparatus comprising:

  • a first control and communications unit 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, said first control and communications unit having means for producing a characteristic signal when the first control and communications unit is operational; and

    a second control and communications unit adapted to monitor the characteristic signal produced by said first control and communications unit and to establish communications over said connected telephone line and transmit an alarm upon interruption of said characteristic signal.

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