scope:

When 64 kbit/s traffic channels are used on the Abis interface, the speech shall be coded according to CCITT 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).