Patent ID: 6978130

Claim:
A method for changing a voice coding mode in a communication system including first and second networks interconnected with each other, at least one first terminal having a voice codec allowing any voice coding mode to be selected from a plurality of voice coding modes, and connected to said first network by a radio link, and at least one second terminal connected to said second network and given by said second network a voice codec allowing any voice coding mode to be selected from a plurality of voice coding modes to communicate with said first terminal, comprising the steps for: in said first network, monitoring the communication situation including quality of the radio link during voice communication of said first terminal; determining an appropriate voice coding mode based on said communication situation; and sending to said first terminal a first request for change to said appropriate voice coding mode; in said first terminal, sending to said second network a second request for change of the voice coding mode upon reception of said first request from said first network; in said second network, changing the voice coding mode of the voice codec given to said second terminal making voice communication with said first terminal upon reception of said second request from said first terminal, and sending back to said first terminal a response to said second request; and in said first terminal, sending back to said first network a response to said first request.