scope:

The present document provides a description of user, functional and some technical aspects of an IP-based text telephony solution known and deployed as "Reliable RTT", supporting the use of fixed and mobile mainstream devices.

The present document provides a pointer to the source where the full details of the implementation, including a private Session Initiation Protocol header and some SIP examples, are made openly and freely available to any developer, service provider or other stakeholder interested in the solution.

The present document carries no operational, interoperability or other requirements on terminal manufacturers, software developers or fixed or mobile network operators or service providers or their regulators, who are not involved in the provision of the solution described.