System for multiplexed communication between exchanges

A method of conducting multiplexed communication between first and second exchanges, comprising steps of:

• detecting occurrence of a compressible call from said first exchange to said second exchange;
• setting up a circuit between multiplexing ports of said first and second exchanges;
• transferring call control information via said circuit set between said exchanges for controlling said call after said circuit has been set up;
• connecting said call to multiplexed ports of said exchanges through multiplexing/demultiplexing means interposed between said multiplexing ports and said multiplexed ports for interconnection thereof;
• connecting any other compressible call occurring after said call to said multiplexed ports;
• starting a count of time by time measuring means when said circuit between said multiplexing ports of said first and second exchanges is set-up;
• checking whether a call exists on said circuit when said time measuring means counts up a predetermined time:
• and
• releasing said circuit when no call exists on said circuit or restarting the count in said time measuring means when a call exists on said circuit;
• starting a count of time by said time measuring means when the circuit failed to be set-up between said multiplexing ports;
• connecting any other compressible call occurring subsequently between the exchanges by using an alternative route:
• and
• trying again a circuit set-up between said multiplexing ports after lapse of a predetermined time;
• wherein when the circuit set-up succeeds, call connection is realized by using said multiplexing/demultiplexing means for compressible calls occurring thereafter between the exchanges.

A multiplexed communication system for multiplexed communication between a plurality of exchanges, comprising at each exchange:

• multiplexing/demultiplexing means for compressing and multiplexing data inputted from first input/output ports to thereby output compressed and multiplexed data to second input/output ports and for demultiplexing and expanding data inputted from said second input/output ports to thereby output demultiplexed and expanded data to said first input/output ports;
• call control information messaging means for messaging control information for controlling calls between said exchanges;
• first detection means for detecting an occurrence of a compressible call to be connected to said first input/output ports;
• means for, upon detection of a compressible call by said first detection means, setting up a circuit through an ISDN exchange network between said exchanges to interconnect said second input/output ports of said multiplexing/demultiplexing means, said call control information messaging means transferring control information through said circuit for controlling said compressible call to thereby connect said compressible call to said first input/output ports between said exchanges;
• second detection means for detecting whether all calls connected to said first input/output ports have been cleared;
• means for, upon detecting that all the calls connected to said first input/output ports have been cleared, releasing said circuit through said ISDN exchange network between said exchanges;
• and
• time measuring means for measuring a time duration of a communication between said exchanges when said circuit is setup between said exchanges and for checking whether a call exist on said circuit, said time measuring means is reset when upon checking it is determined that a call exists on said circuit and said circuit is released when upon checking it is determined that a call does not exist on said circuit.

A system for multiplexed communication between a plurality of exchanges, comprising at each exchange:

• multiplexing/demultiplexing means for compressing and multiplexing data inputted from first input/output ports to thereby output compressed and multiplexed data to second input/output ports and for demultiplexing and expanding data inputted from said second input/output ports to thereby output demultiplexed and expanded data to said first input/output ports;
• call control information messaging means for messaging control information to control calls between said exchanges;
• first detection means for detecting an occurrence of a compressible call to be connected to said first input/output ports;
• means for, upon detection of a compressible call by said first detection means, setting up a circuit between said exchanges to interconnect said second input/output ports of said multiplexing/demultiplexing means, said call control information messaging means transferring control information through said circuit for controlling said compressible call to thereby connect said compressible call to said first input/output ports between said exchanges;
• second detection means for detecting whether all calls connected to said first input/output ports have been cleared;
• and
• means for, upon detecting that all the calls connected to said first input/output ports have been cleared, releasing said circuit between said exchanges;
• wherein at each exchange said system further comprises:
• a first time measuring means for measuring a time duration of a communication between said exchanges when said circuit is setup between said exchanges and for checking whether a call exist on said circuit, said first time measuring means is reset when upon checking it is determined that a call exists on said circuit and said circuit is released when upon checking it is determined that a call does not exist on said circuit;
• wherein when the circuit between the exchange has not been set up, a second time measuring means is started and circuit setup for interconnecting said multiplexing/demultiplexing means is tried after a time duration measured by said second time measuring means has attained a predetermined time, and said second time measuring means is reset it the circuit between the exchanges has not been set up.