| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a session establishment technique capable of suppressing a performance required of a call control server and communication traffic to be low. <P>SOLUTION: IP telephone terminals 1-2 and 1-3 with an SIP server function of a call destination and a call origin acquire IP addresses of each other by transmitting and receiving an INVITE message and a 302 Redirect message through an IP telephone terminal 1-1 with the SIP server function functioning as an SIP server (S102-S108). Then, the IP telephone terminals 1-2 and 1-3 with the SIP server function of the call destination and the call origin directly transmit and receive an SIP message without interposing the IP telephone terminal 1-1 with the SIP server function functioning as the SIP server by using the IP addresses of each other and thus execute an SIP sequence to establish a session between the IP telephone terminals 1-2 and 1-3 (S109-S118). <P>COPYRIGHT: (C)2012,JPO&INPIT |
