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Two-line apparatus for telephone intercom

  • US 5,781,622 A
  • Filed: 05/05/1995
  • Issued: 07/14/1998
  • Est. Priority Date: 04/08/1990
  • Status: Expired due to Fees
First Claim
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1. Apparatus for providing an intercom function on a telephone having DTMF or pulse capabilities including at least one intercom operation device arranged for connection to a DTMF or pulse telephone line and to a DTMF and pulse telephone instrument and comprising:

  • means for sensing a received extension address signal along the telephone line, determining whether the address corresponds to the telephone instrument to which the intercom operation apparatus is connected and, upon determination of correspondence, providing an extension selection ring output, and an internal power supply wherein said power supply uses only the telephone line voltage;

    an internal DTMF receiver circuit unit, an internal pulse receiver and an identification integrated circuit unit and a buzzer; and

    wherein the internal power supply unit provides 3-5 volts to the system and 2.5-3 milliampere during operation.

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