4 High level Requirements

22.2263GPPGlobal Text Telephony (GTT)Release 15Stage 1TS

The following list gives the high level requirements of the GTT. These are requirements which are independent of the user’s perception of the feature:-

– Service definition

Global Text shall provide a real time conversational text feature. A general definition is found in Recommendation ITU-T F.700[5].

– Global Text Telephony host environments

A standardised method for Global Text Telephony shall at least be specified for each host environment in the mobile networks that can carry voice.

– Standards compliant and forward compatible text conversation

Global Text Telephone mechanisms shall provide the capability to support current and evolving text telephony and text conversation features by re-using existing standards as far as possible and proposing extensions (as necessary) to existing standards (i.e. the global text telephony feature shall support the evolution of Total Conversation technologies in all networks).

– Consistent text conversation

Regardless of the selected host environment, the far end terminal, the interworking facilities involved, GTT shall be capable of providing a consistent way of handling the conversation.

– Global Text Telephone access

Within the capabilities of networks and terminals, the user shall be provided consistent access to the GTT regardless of the access point.

For example: the user shall be capable of accessing the text conversation features through a number of different access points, including networks based on 3GPP specifications, access through dedicated multimedia terminals, and access through combinations of mobile phones combined with text user interface devices.

– Interoperability

Global Text Telephony shall support interoperability with existing and emerging text telephone systems and text conversation features.

Global Text Telephony shall support a minimum set of environments where text conversation is supported to ensure full interoperability between different terminals and networks.

– Emergency calls

The implementation of Global Text Telephony shall enable a user to make emergency calls to, and receive calls from, an emergency call centre via a text telephony device used in conjunction with GTT enabled user equipment.