Importance

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Abstract

An apparatus for providing passive bus communication in an ISDN without use of services of a central office includes a passive bus suitable for ISDN D-channel frame communication, the passive bus having an echo channel and having a plurality of terminal devices coupled to the passive bus. A receiving circuit is coupled to the passive bus for receiving D-channel frames containing a SAPI address transmitted from the terminal devices over the passive bus. A decoding circuit is coupled to the receiving circuit for decoding D-channel addresses transmitted from the terminal devices over the passive bus. The decoding circuit includes a circuit for determining if one of the D-channel frames from the terminal devices include a predetermined SAPI address. A switching circuit is coupled to and responsive to the decoding circuit, and implements a logical communication channel between two or more of the plurality of terminal devices when the D-channel frame includes the predetermined SAPI address. The switching circuit echoes D-channel frames over the echo channel of the passive bus for receipt by the terminal devices (TE) coupled to the passive bus and inhibits transmission of the D-channel frames to the central office when the D-channel frames include the predetermined SAPI address. The TE monitors the D-echo channel to receive the local passive bus communication in addition to contention resolution.

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First Claim