8 External Interfaces
22.2263GPPGlobal Text Telephony (GTT)Release 17Stage 1TS
8.1 External interfaces in the terminal
It shall be possible to control and operate GTT from external digital devices, e.g, portable computers. For this purpose interfaces shall be standardised between the terminal and such external digital devices.
It shall be possible to control and operate GTT from external analogue text telephones. For this purpose, interfaces shall be standardised between the mobile terminal and such external analogue text telephones.
External interfaces specified for controlling and operating GTT between the terminal and an external device should make it possible to use the external device for both Multimedia Messaging and GTT.
8.2 External interfaces to other networks
No new network interfaces shall be specified for GTT, only the necessary elements to accomplish text interworking. These are specified in ITU-T H.248 Annex F, in the Text Conversation and Text Telephone packages [3].
The networks for specified interworking include:
– PSTN for interworking with PSTN text telephones.
– IP networks for interworking with IP conversational multimedia terminals and IP text telephones.
– CS networks for interworking with CS Multimedia terminals.
– Mobile networks out of scope of the GTT specifications interface through common interworking facilities.