scope:

When 64 kbit/s traffic channels are used on the Abis interface, the speech shall be coded according to ITU-T Recommendation G.711 and the data rate adaptation shall be as specified in GSM 04.21 and GSM 08.20.

In the case where 16 kbit/s traffic channels are used for full rate speech, enhanced full rate speech, Adaptive Multi-Rate speech or full rate data service, then the present document shall apply for frame structure and for control of remote transcoders and additional rate adaptors.

For Adaptive Multi-Rate speech the present document specifies the 16 kBit/s submultiplexing, both for the full and the half rate traffic channels (TCH/AFS and TCH/AHS). The specification for 8 kBit/s submultiplexing is given in GSM 08.61, both for the full and the half rate traffic channels (TCH/AFS and TCH/AHS).

The use and general aspects of the Abis interface are given in GSM 08.51.

NOTE: The present document should be considered together with the GSM 06 series of specifications, GSM 04.21 (Rate Adaptation on the MS-BSS Interface) and GSM 08.20 (Rate Adaptation on the BS/MSC Interface).