A.2 GTT-Voice specific information for CTM support in or associated with all transcoders in the core network for networks supporting the Iu interface

23.2263GPPGlobal Text Telephony (GTT)Release 17Stage 2TS

For networks with GERAN and UTRAN radio access using the Iu interface, the CTM detection/conversion function may be incorporated in all transcoders where CTM activity can realistically be expected. It is also an option to incorporate a CTM detection/conversion function in separate entity associated with the Transcoder.

The CTM adapter automatically detects the presence of CTM encoding and provides the necessary conversion to the appropriate ITU‑T Recommendation V.18 [4] modem encoding.

Figure A.2: Association of a CTM adapter with the transcoder in the core network

Due to the presence of the CTM detection/conversion function in all circuits, no CTM capability information needs to be signalled to the network by the mobile.

Annex B (informative):
GTT-Voice support via selection of CTM detection / conversion function