A new standard extending support of a key communications tool for the deaf and hard of hearing to IP-based networks was consented at a recent meeting of ITU-T’s Study Group 16. The continued support of textphones (TTYs) as operators increasingly shift to IP is important for the many thousands of users of these systems.

The announcement marks a key milestone in the development of what ITU terms Total Conversation, that is the convergence of voice, video and text telephony.

The new standard known as ITU-T Recommendation V.151 relates to text over IP (ToIP). ToIP is the transport of real-time text over IP networks. It differs from instant messaging in that ToIP systems transmit bi-directionally, one character at a time. This gives the user the feel of real-time communication, just like voice or video systems that transport streaming media over IP.

ToIP services are available using a legacy textphone (TTY) which has long been the preferred tool of the deaf and hard of hearing, an enabled IP phone or a PC-based client.

V.151 has an important role to play in the protection of text quality when transported through IP networks, also offering the potential to enable communication between earlier incompatible textphones from different regions.