V.151

V.151 is a standard from the ITU that specifies how to transport PSTN textphone signals over IP networks between two gateway devices, including PSTN gateways and residential gateways. It relies upon RFC 4351 for the descriptions of how to transport characters extracted from the textphone signaling via RTP.

V.151 is a standard that may be used with all of the major VoIP protocols, including H.323, SIP, H.248, and MGCP.

Resources: ToIP Information Site

See Also: Textphone, Telecommunication Device for the Deaf (TDD), Teletypewriter (TTY)