When 64 kbit/s traffic channels are used on the A-bis interface, the speech shall be coded according to ITU-T Recommendation G.711 and the data rate adaptation shall be as specified in TS 04.21
and TS 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 this TS shall apply for frame structure and for control of remote transcoders and additional rate adaptors.
For Adaptive Multi-Rate speech this TS 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 TS 08.61
, both for the full and the half rate traffic channels (TCH/AFS and TCH/AHS).
The use and general aspects of the A-bis interface are given in TS 08.51
This TS should be considered together with the GSM 06 series of specifications, TS 04.21 (Rate Adaptation on the MS-BSS Interface) and TS 08.20 (Rate Adaptation on the BS/MSC Interface).