| 摘要 |
<p>A method and a system for implementing Color Ring Back Tone (CRBT) and Color Ring Tone (CRT) services are provided. The method for implementing CRBT service comprises the following steps of: a calling party sending a call originating request carrying a Session Description Protocol (SDP) request of a normal session to a called party through a conversion Application Server (AS) and a CRBT Sever, and the called party sending a temporary response to the calling party upon receiving the call originating request; upon receiving the temporary response, the CRBT Server adding a SDP offer for CRBT to the temporary response according to an indication of supporting SDP for CRBT service carried in the call originating request and sending to the calling party; upon receiving the temporary response, the conversion AS generating a SDP answer based on the SDP offer for CRBT and sending the temporary response containing only the SDP answer to the calling party; the calling party sending a Pre-Acknowledgement (PRACK) message to the called party upon receiving the temporary response; the conversion AS generating a SDP answer for CRBT based on the SDP offer for a normal session upon receiving the PRACK message and sending the SDP answer for CRBT to the CRBT Server by including the SDP answer for CRBT in the PRACK message, the CRBT Server completing CRBT media negotiation according to the SDP answer for CRBT.</p> |
