3 Definitions and abbreviations

22.0533GPPRelease 17Service descriptionStage 1Tandem Free Operation (TFO)TS

GSM 01.04 [2] provides a list of abbreviations and acronyms used in GSM specifications.

3.1 Definitions

For the purposes of the present document, the following terms and definitions apply:

Tandem Free Operation (TFO): avoidance of tandeming speech codecs in mobile to mobile speech calls

TFO call: mobile to mobile call where TFO has been applied

Normal call or operation: call where TFO has not been applied

Negotiation phase: phase during which the applicability of TFO is assessed through the exchange of information such as the capabilities of the respective transcoders and the types of speech codecs being used

A party: user originating the call

B party: user receiving the call (unless the call is forwarded)

For simplicity the term MS is also used when UE is meant for 3G systems. The same is valid for TRAU and TC analogously.

3.2 Abbreviations

For the purposes of the present document, the following abbreviations apply:

ASCI Avanced Speech Call Items

MSC Mobile services Switching Centre

PLMN Public Land Mobile Network