The transcoding procedure specified in this European Telecommunication Standard (ETS) is applicable for the full-rate Traffic Channel (TCH) in the digital cellular telecommunications system. The use of this tra nscoding scheme for other applications has not been considered. In GSM 06.01, a reference configuration for the speech transmission ch ain of the digital cellular telecommunications system is shown. Accord ing to this reference configuration, the speech encoder takes its inpu t as a 13 bit uniform PCM signal either from the audio part of the mob ile station or on the network side, from the PSTN via an 8 bit/A-law t o 13 bit uniform PCM conversion. The encoded speech at the output of t he speech encoder is delivered to a channel encoder unit which is spec ified in GSM 05.03. In the receive direction, the inverse operations t ake place. This ETS describes the detailed mapping between input blocks of 160 sp eech samples in 13 bit uniform PCM format to encoded blocks of 260 bit s and from encoded blocks of 260 bits to output blocks of 160 reconstr ucted speech samples. The sampling rate is 8000 sample/s leading to a n average bit rate for the encoded bit stream of 13 kbit/s. The coding scheme is the so-called Regular Pulse Excitation - Long Term predicti on - Linear Predictive Coder, here-after referred to as RPE-LTP. This ETS also specifies the conversion between A-law PCM and 13 bit un iform PCM. Performance requirements for the audio input and output par ts are included only to the extent that they affect the transcoder per formance. The ETS also describes the codec down to the bit level, thus enabling the verification of compliance to the ETS to a high degree o f confidence by use of a set of digital test sequences. These test seq uenc s are described and are included in this ETS on diskette.