Patent ID: 8515769

Claim:
An apparatus, comprising: a receiver, of a first mobile switching center, configured to receive an input signal in a first encoding format, the input signal having an input payload and wherein the first encoding format is a dual-mode InterSystem Link Protocol (ISLP)/Enhanced Variable Rate Coding (EVRC) codec; and a transcoder operatively coupled to the receiver, the transcoder structured to transcode in a single channel the first encoding format to a second encoding format, the transcoder configured to generate an output signal, in the second encoding format for transmission over an internet protocol (IP) network to a second mobile switching center, based on the input signal, the output signal having an output payload based on the input payload and wherein the second encoding format is a G.711 codec; and wherein the transcoder is configured to switch between a default voice handling mode for the EVRC codec and a clear channel mode for the ISLP codec to form the output payload; wherein the switching between the default voice handling mode and the clear channel mode is based on a trigger; wherein the trigger is a sequence of Dual Tone MultiFrequency (DTMF) digits that occur in band in a bearer stream to effect switching between the default voice handling mode and the clear channel mode.