Method for performing continuity check in an electronic exchange system

An apparatus for performing a continuity check on a speech channel in an electronic exchange system utilizing a common channel signalling system, wherein a digital signal channel is separated from the speech channel, said apparatus comprising:

• trunk control means for checking and controlling a continuity of the speech channel by generating a continuity check request;
• common channel signalling means for transmitting call messages, said common channeling signalling means further performing message discrimination, message distribution, message routing, signalling a link manager, signalling link activation, signalling link deactivation and updating local routing table functions;
• service circuit means for generating and receiving a continuity check tone in response to said continuity check request;
• means for detecting a trunk call of a first subscriber, in order to confirm whether said trunk call has been established;
• trunk sharing means for enabling a plurality of the speech channels to be carried within a trunk module;
• and
• digital switching means for interfacing said trunk control means, common channel signalling means, service circuit means, means for detecting a trunk call, and trunk sharing means.

A method of performing a continuity check on a speech channel in an electronic exchange system utilizing a common channel signalling system, wherein a digital channel is separated from the speech channel, said method comprising:

• transmitting a continuity check request on a continuity check indicator located in a header of a call message if a first trunk module generates said continuity check request while handling an outgoing trunk call to a second trunk module located within one of said electronic exchange system and a different electronic exchange system by making a determination if said continuity check request is on said continuity check indicator, delivering said continuity check request to a preselection call control, and requesting a continuity loop connection;
• connecting the speech channel with a continuity check tone transceiver to transmit a continuity check tone on the speech channel;
• making a determination whether said continuity check tone transmitted on a forward channel of the speech channel is received back through a back channel of the speech channel within a predetermined amount of time;
• and
• terminating transmission of said continuity check tone, stopping a timer from counting and disconnecting said continuity check tone transceiver from said speech channel if said continuity check tone is received back through said back channel within said predetermined amount of time.

A method of establishing continuity check message flow between a first and a second electronic exchange system utilizing a common channel signalling system, wherein a continuity check of an idle speech channel is performed, said method comprising:

• transmitting a continuity check request from said second electronic exchange system to said first electronic exchange system;
• connecting said second electronic exchange system with a continuity check tone transceiver;
• connecting said first electronic exchange system with a continuity check-loop upon receipt of said continuity check request from said second electronic exchange system;
• disconnecting said second electronic exchange system from said continuity check tone transceiver and sending a clear forward message from said second electronic exchange system to said first electronic exchange system, if a continuity check tone transmitted through a transmission channel of the speech channel by said continuity check tone transceiver is received through a reception channel of the speech channel within a predetermined amount of time;
• placing the speech channel back to said idle state if said second exchange system receives a release guard signal;
• and
• disconnecting said second electronic exchange system from said continuity check tone transceiver, if said continuity check tone transmitted through said forward channel of the speech channel is not received back through said back channel of the channel within said predetermined amount of time.

A method of establishing continuity check message flow between outgoing and incoming electronic exchange systems utilizing a common channel signalling system, wherein a continuity check of an engaged speech channel is performed, said method comprising:

• indicating a continuity check request on a continuity check indicator located in a head address message and connecting said engaged speech channel to a continuity check tone transceiver, if said outgoing electronic exchange system makes a determination to perform the continuity check;
• connecting a continuity check-loop with said engaged speech channel upon receipt of said continuity check request by said incoming electronic exchange system;
• transmitting a class of trunk message from said outgoing electronic exchange to said incoming electronic exchange to release said continuity check-loop, having said incoming electronic exchange release said continuity check-loop, sending an address complete message to said outgoing electronic exchange and sending a ringing tone to a called subscriber, if said continuity check is terminated;
• sending an answer charging message from said incoming electronic exchange to said outgoing electronic exchange and establishing a speech connection between said incoming and outgoing electronic exchanges, if said called subscriber picks up a receiver;
• sending a clear forward signal from said outgoing electronic exchange to said incoming electronic exchange if a calling subscriber hangs up before said called subscriber to indicate that a forward channel of said engaged speech channel is released;
• and
• sending a release guard signal from said incoming electronic exchange to said outgoing electronic exchange to indicate that said speech communication is completed.

A circuit for performing a continuity check on a speech channel in an electronic exchange system utilizing a common channel signalling system, said circuit comprising:

• means for checking and controlling a continuity of said speech channel by generating a continuity check request;
• common channel signalling means for performing message transmission functions and processes pertaining to a message transmission through signalling data links, and performing common and individual functions and processes pertaining to said signalling data links;
• means for transmitting and receiving a continuity check tone to test said continuity of said speech channel in response to said continuity check request;
• tinting means for measuring an amount of time for said means for transmitting and receiving a continuity check tone to receive said continuity check tone after transmitting said continuity check tone;
• means for detecting incoming and outgoing calls of a first subscriber of said electronic exchange system;
• and
• digital switch means for interfacing said means for checking and controlling a continuity of said speech channel, said common channel signalling means, said means for transmitting and receiving a continuity check tone and said means for detecting incoming and outgoing calls of a first subscriber.