Patent ID: 8199727

Claim:
A serving mobile switching center (MSCe) for call delivery to a mobile station serviced by a wireless communication network, comprising: circuitry operable to receive call signals indicating a call setup with the mobile station of a called party; circuitry operable to perform the call setup to establish a communication link with the mobile station, further including circuitry for determining whether to provide ringback to a mobile station of a calling party; and wherein the serving MSCe is further operable to: receive a prioritized list of voice CODECs (SDP-IS) in a Session Initiation Protocol (SIP) call origination message, the SDP-IS including a list of prioritized voice CODECs received by a gateway MSCe relating to the call setup; provide a requested voice codec list to the mobile station of the called party; receive a list of supported voice CODECs from the mobile station of the called party; receive a list of supported transcoders from a base station serving the mobile station of the called party; perform transcoder free operation (TrFO) or remote transcoder operation (RTO) based upon the prioritized list of voice CODECs, the list of supported voice CODECs from the mobile station of the called party, and the list of supported transcoders from the base station serving the mobile station of the called party and assigns transcoders in at least one of a serving media gateway (MGW) and a serving base station (BS) for a voice bearer path between the mobile stations of the calling party and of the called party; and initiate a ringback to the mobile station of the calling party, wherein, when ringback is initiated, then any time after the SIP call origination message has been received for call setup, the MSCe is operable to send a 180 Ringing message to the network supporting the mobile station of the calling party, the 180 Ringing message is a signaling command to the network supporting the mobile station of the calling party to also ringback to the mobile station of the calling party.