08.623GPPInband Tandem Free Operation (TFO) of speech codecsService descriptionStage 3TS
For the purposes of the present document, the following terms and definitions apply.
TRAU Frame: is used equivalent to "TRAU Speech Frame".
TFO Frame: is used equivalent to "TFO Speech Frame".
Abis/Ater: indicates that either the Abis or the Ater interface is used, depending on the location of the TRAU equipment.
For the purposes of the present document, the following abbreviations apply.
BSC Base Station Controller
BSS Base Station Sub-system
BTS Base Transceiver Station
EFR Enhanced Full Rate
FR Full Rate
GCME GSM Circuit Multiplication Equipment
HR Half Rate
IPE In Path Equipment
MS Mobile Station
MSC Mobile Switching Centre
PCM sample 8-bit value representing the A_Law or _Law coded sample of a speech or audio signal; sometimes used to indicate the time interval between two PCM samples (125s).
PCM_Silence either PCM_Alaw_Silence, or PCM_Law_Silence, dependent on application
PCM_Alaw_Silence PCM sample with value 0xD5.
PCM_Law_Silence PCM sample with value 0xFF.
PCM_Idle either PCM_Alaw_Idle, or PCM_Law_Idle, dependent on application
PCM_Alaw_Idle PCM sample with value 0x54.
PCM_Law_Idle PCM sample with value 0x00.
TFO_ACK TFO Acknowledgement Message
T_Bits Time Alignment Bits
TFO_FILL TFO Fill Message
TFO_TRANS TFO Transparent Mode Message
TFO_NORMAL TFO Normal Mode Message
TFO_DUP TFO (Half) Duplex Mode Message
TFO_REQ TFO Request Message
TFO_SYL TFO Sync Lost Message
TFO Tandem Free Operation
TRAU Transcoder and Rate Adaptor Unit
Other abbreviations used in this TS are listed in GSM 01.04.