Abstract: Various embodiments are described to address the need for a method and apparatus of voice transcoding in a VoIP environment that effectively interconnects multiple voice encoding formats. In general, a packet-based tandem transcoder (201) receives (706) packets that include vocoder data frames in which source voice samples have been encoded according to a first vocoding format. The transcoder then decodes (708) the vocoder data frames to produce a sequence of linear speech samples. Using a non-circuit switched communication path, an encoder obtains (710) linear speech samples from the sequence of linear speech samples and encodes (712) groups of speech samples from the sequence of linear speech samples to produce vocoder data frames according to a second vocoding format.

Abstract: A third generation (3G) gateway (30) provides the facilities for extending a number of internet protocols (40, 64, 74, 83, 100, 110, 120 and 130) between a second generation (2G) network and a 3G network. The various messages of a session initiation protocol (SIP) are extended to provide user identification and server identification subfields (42). The SIP message extensions facilitate the communication of 2G and 3G networks for the purposes of implementing push-to-talk and dispatch service features.

Abstract: A third generation (3G) gateway (30) provides the facilities for extending a number of internet protocols (40, 64, 74, 83, 100, 110, 120 and 130) between a second generation (2G) network and a 3G network. The various messages of a session initiation protocol (SIP) are extended to provide user identification and server identification subfields (42). The SIP message extensions facilitate the communication of 2G and 3G networks for the purposes of implementing push-to-talk and dispatch service features.

Abstract: A transcoder (40) includes a method for assigning transcoder channel elements (43, 44). The transcoding assignment method selects a DSP (60-75) selects a DSP (channel element) of the required type which has available channel elements (98). Further, the transcoding assignment method may dynamically reassign (118) DSPs from one channel element type to another.