scope:

The transcoding procedure specified in the present document is applicable for the full-rate traffic channel (TCH) in digital cellular telecommunications system. The use of this transcoding scheme for other applications has not been considered. In recommendation GSM 06.01, a reference configuration for the speech transmission chain of the digital cellular telecommunications system is shown. According to this reference configuration, the speech encoder takes its input as a 13 bit uniform PCM signal either from the audio part of the mobile station or on the network side, from the PSTN via an 8 bit/A-law to 13 bit uniform PCM conversion. The encoded speech at the output of the speech encoder is delivered to a channel encoder unit which is specified in Rec.GSM 05.03. In the receive direction, the inverse operations take place.