Patent ID: 6577638
Filing Date: 2003-06-10
Classification: H04L

Abstract:
A gateway connected to the Internet and a telephone exchange accommodating a plurality of terminals and carrying out routing optimization processing based on a first message used as a request for path optimization, said gateway comprising:a call setting means for: determining an IP (Internet Protocol) address of a second gateway corresponding to a calling-destination special number of a called telephone exchange used as a called communication partner and connected to said second gateway on the basis of a second message which is received from said connected telephone exchange, includes said calling-destination special number of said called telephone exchange and a telephone number of a called terminal accommodated in said called telephone exchange and serves as a request for call setting; and transmitting a third message serving as a request for said call setting to said second gateway serving as a communication partner by using said IP address by way of said Internet to open a control channel to said second gateway; a first message transmitting means for setting a fourth message received from said connected telephone exchange in a message to be transmitted by using said control channel and transmitting said message to said second gateway serving as a communication partner by way of said Internet; a second message transmitting means for extracting a fifth message and transmitting said fifth message to said connected telephone exchange when receiving a message coming from said control channel and including said fifth message set therein and transmitted by said called telephone exchange; an audio-channel opening means for opening an audio channel for a conversation between a calling terminal accommodated in said connected telephone exchange and said called terminal when receiving a message including a set sixth message issued by said called telephone exchange serving as a called communication partner through said control channel in response to said second message; and a channel releasing means for releasing said control channel and said audio channel when receiving a message including a set seventh message serving as a request for releasing of said control channel and said audio channel from said control channel.