MULTICAST COMMUNICATION METHOD

PROBLEM TO BE SOLVED: To eliminate the need for transmission of a call control message to a terminal having already taken part in communication when the terminal or a transmission channel is added during the communication and for decreasing a connection delay until data reception is actually started. SOLUTION: When starting communication, a server 100 assigns a plurality of multicast channels to the communication in advance and instructs the terminals A101, B102 to receive all the channels, and the terminals are put in such a state as to receive all the multicast channels designated by the reception instruction of a call control message when the communication is started. Thus, when a terminal C103 participates during the communication, the server 100 has only to instruct the terminal C103 participating during the communication to make transmission to a channel to which no terminal is making transmission among multicast channels assigned when the communication is started and does not need to transmit the call control message to the initial participation terminals which have already taken part in the communication. COPYRIGHT: (C)2005,JPO&NCIPI