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ISDN terminal adapter for use with external modem and employing software-based serial communication framing for ISDN `D` channel signaling

  • US 5,903,572 A
  • Filed: 09/04/1997
  • Issued: 05/11/1999
  • Est. Priority Date: 04/22/1996
  • Status: Expired due to Term
First Claim
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1. An apparatus for interfacing digital terminal equipment with a communication link, said apparatus comprising:

  • a transceiver which is operative to send and receive digital communication signals via said digital communication link;

    a first digital port to which a digital communication port of said digital terminal equipment is connectable;

    a second digital port to which a digital communication port of a modem is connectable;

    a first analog port to which an analog communication port of said modem is connectable;

    a first analog/digital communication interface coupled between said first analog port and said first transceiver; and

    a communication processor, coupled with said first and second digital ports and said transceiver, and being operative to control establishment of digitally formatted communications through said modem between said digital terminal equipment and said communication link, by selectively providing one of;

    1--a first path, exclusive of said modem, between said first digital port and said first transceiver, and2--a second path, inclusive of said modem, between said transceiver and said first analog/digital communication interface.

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