| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To efficiently utilize bands and prevent congestion caused by call admission control (CAC). <P>SOLUTION: A proxy server 3 selects PCM with a larger consumption band from CS-SELP (8 kbps) and PCM (64 kbps) designated in a received SIP request, and transfers a SIP request to a proxy server 5 when it is determined that the band of PCM is ensured. The proxy server 5 performs the same processing as in the proxy server 3. A user agent server (UAS) 6 sends a SIP response which selects CS-ACELP as a codec to be used in RTP. The proxy servers 5 and 3 confirm the codec designated in the SIP response, correct the information of the band in use calculated when transferring the SIP request and transfer the SIP response to a user agent client (UAC) 1. The proxy servers 3 and 5 confirm the contents of the messages of the SIP request and SIP response and ensure an exact band to be actually utilized by RTP. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
