| 摘要 |
A system and a method in a wireless network utilizing session initiation protocol (SIP) for call control. The SIP payload (SDP) contains a list of voice codecs to coordinate the selection of voice bearer resources (between a calling party and a called party) such that the number of transcoders in the voice bearer path is minimized. An additional aspect of the embodiment of the present invention includes a serving MSCe that is operable to determine whether to initiate or discontinue ringback to the calling party. If ring back is to be initiated, ringback can be initiated from a Serving MGW controlled by the serving MSCe. The call negotiation process according to the described embodiment of the invention eliminates the requirement for any transcoding in specific situations to result in the number of transcoders used in the voice bearer path to be reduced to 0 (TrFO, Transcoder Free Operation) or to 1 (RTO, remote transmitter operation).
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