This 3GPP Technical Specification defines the stage 2 description of the real time Text Conversation Feature called Global Text Telephony, GTT. GTT Stage 2 identifies the functional capabilities needed to support the service described in GTT Stage 1.

This TS contains the core functions for a real time Text Conversation Feature GTT, to be used in combination with other media in conversational services.

GTT offers real time conversation in text, to be used alone or in combination with other conversational media, and interworking with current and emerging text conversation features in the fixed networks and other mobile networks.

GTT uses a number of functional entities to realise the requirements of the stage 1 description (TS 22.226 [3]). This TS describes how the service requirements are realised with these functional entities. As far as possible existing protocols shall be used for the realisation of the Global Text Telephony Feature. This may include e.g. , SIP, 3G.324, or Circuit Switched Voice service as protocol environments, and CTM, AL1 and RTP/text as transmission protocols. It also means usage of existing text presentation format ITU-T Recommendation T.140 [5], common to all GTT text conversation environments.