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Communication line backup system

  • US 5,406,564 A
  • Filed: 11/22/1991
  • Issued: 04/11/1995
  • Est. Priority Date: 11/27/1990
  • Status: Expired due to Fees
First Claim
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1. A communication line backup system which provides a backup line for backing up a communication line which connects first and second subscriber terminals when a failure is generated on the communication line between the first and second subscriber terminals, said communication line backup system comprising:

  • a first backup unit coupled to the first subscriber terminal;

    a second backup unit coupled to the first subscriber terminal;

    an integrated services digital network (ISDN) coupled to said first and second backup units via ISDN channels,said first and second backup units further including backup means for forming a backup communication channel between the first and second subscriber terminals in response to the failure generated on the communication line between the first and second subscriber terminals,said backup communication channel being formed by at least one channel within the ISDN channels established in said integrated services digital network,said backup means of said first backup unit including backup instruction receiving means for receiving a backup instruction transmitted from an external device; and

    said backup means at said first backup unit further including an ISDN interface circuit for converting bipolar type information into unipolar type information and for converting unipolar type information into bipolar type information.

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