What is the technology behind real-time text?
At the core of the framework for real-time text over Internet Protocol (IP) networks is the Session Initiation Protocol (SIP) and the real-time text transport standard, as currently described in IETF RFC 4103. This framework is designed to be compatible with voice over IP (VoIP) and streaming video environments. It also builds upon, and is compatible with, the high-level user requirements of deaf, hard of hearing, and speech-impaired users, as described in RFC 3351. RFC 5194 describes the defined framework for implementation of all required functions based on the Session Initiation Protocol (SIP) and the Real-Time Transport Protocol (RTP). This document also describes the essential requirements for real-time text-over-IP and the interworking between text-over-IP and existing text telephony on the Public Switched Telephone Network (PSTN) and other networks.
