10 Additional services

22.2263GPPGlobal Text Telephony (GTT)Release 17Stage 1TS

10.1 Emergency services

It shall be possible to support emergency service calls with text and voice.

If an emergency service centre supports call back to the calling user, then the call-back function shall be available for GTT text calls without modification to the existing emergency service centre text telephony equipment.

GTT emergency calls shall be possible without the SIM/USIM module in the same host environments as such calls are enabled for voice.

All information that follows a voice call to the emergency centre, shall also be provided to the centre if GTT text is used in the call.

The emergency service requirements shall be possible to fulfil for emergency service centres equipped with PSTN text telephones, operated through a relay operator service or an interworking functions.

Support of GTT service for emergency calls shall not jeopardise normal emergency calls.

10.2 Relay services

Relay services offer translation between text and voice. It is most commonly implemented as manned services.

Access to relay services shall be possible for GTT users. Establishment of the relay service itself is outside the scope of GTT.

GTT shall enable addition of a relay service to the call. The relay service terminates the text path, and translates between text and voice.

Addressing the destination and requesting support from the relay service should be possible to do in one operation from the GTT user.

Other aspects of implementing relay services are outside the scope of this specification.