Support of ToIP is being considered in multimedia Emergency Public-safety answering point (PSAPs) in Europe and USA.
The ECRIT IETF working group defines ToIP as one form of access to Emergency Services.
A typical terminal on a fixed line access is a home computer that supports multimedia communications - Voice and Video and real-time Text over IP.
Telecommunications device for the deaf (TDD) or TTYs (also called Textphone or minicoms) were designed to transport real-time text over the PSTN.
Text-over-IP has been designed as a replacement for TDDs when using the IP-based networks but also to be of use to mainstream voice call users.
Interworking between TDDs and ToIP has been implemented using gateways by T-Meeting, Omnitor, Trace R& D, RNID, Center, Voiceriver, and AnnieS.
RFC 5194 "Framework for real-time text over IP using the Session Initiation Protocol (SIP)" provides an overview of interworking issues.