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Digital PBX integrated workstation security system

  • US 4,654,640 A
  • Filed: 12/03/1985
  • Issued: 03/31/1987
  • Est. Priority Date: 12/03/1985
  • Status: Expired due to Fees
First Claim
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1. Security system apparatus, for use with a time division multiplexed (TDM) digital PBX telephone system of the type having a time slot interchange (TSI) switch matrix with signal ports for exchanging control channel, voice channel and data channel signal bits between those signal ports identified by a PBX call processor, the ports each adapted for connection to telephone signal equipment, for detecting removal of protected equipment from remote site locations, the apparatus comprising:

  • tether means, one for each protected equipment, each having signal conductors joined at one end by security connector means to provide an electrically continuous loop with said security connector attached to the protected equipment, and to provide an electrically discontinuous loop with removal of said connector from the equipment;

    plurality of security monitor means, each connected for response to a group of said tether means and each adapted to exchange data channel signal bits between the data channel of local telephone signal equipment and each of said tether means connected thereto, to determine the presence of said electrically continuous and said electrically discontinuous loop conditions, and to provide security signal indications of each condition to the telephone signal equipment data channel; and

    security controller means, connected for response to a signal port of the PBX switch matrix and responsive to the PBX call processor and to the data channel signals of the PBX telephone signal equipment, said controller having memory means for storing signals and having signal processing means for receiving, and storing in said memory means, said security signal indications of said discontinuous loop conditions from each of said monitor means, and for providing an alarm signal indication of each.

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