ITU-T - International Telecommunication Union/ITU Telcommunication Sector
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ITU-T V.152-2010
Scope
"This Recommendation describes the voice-band data (VBD) operation of Voice-over-Internet Protocol (VoIP) gateways and media gateways. The term ""VBD"" refers only to the use of suitable voice-band codecs for the transport of data payloads via RTP. The VBD procedures described in this Recommendation shall apply to VBD-only capable gateways. An ITU-T V.152 gateway only has the guarantee of interworking with another gateway if that gateway also supports ITU-T V.152. This does not preclude the interworking with non-ITU-T V.152 gateways; however@ there are no guarantees of performance and supported functionality with such systems. The negotiation of a VBD capability does not exclude from a VoIP session any other capabilities such as the transport of audio signals@ RFC 4733-based telephone events@ ITU-T T.38 facsimile relay@ RFC 4103 text relay and ITU-T V.150.1 modem relay@ etc. Declaration of VBD support using the session description protocol (SDP) is detailed in clause 7.1. Declaration of VBD support using ITU-T H.245 is detailed in clause 7.2. This Recommendation supports hybrid modes of operation; for example@ a device may support a VBD and facsimile relay capability but not a modem relay or text relay capability. In this example of hybrid operation modem and text payloads are transported in the VBD mode@ while facsimile payloads could be transported in the ITU-T T.38 facsimile relay mode or in the VBD mode. The negotiation of such hybrid sets of capabilities follows SDP and ITU-T H.245 mechanisms (clause 11). This Recommendation describes the default mechanism for transitioning into VBD mode via payload-type switching as described in clause 10 and the optional mechanism of utilizing the state signalling events (SSE) messages described in clause 11."
ITU-T V.152-2010 history
2010ITU-T V.152-2010 Procedures for supporting voice-band data over IP networks (Study Group 16)
2005ITU-T V.152-2005 Procedures for supporting voice-band data over IP networks Interworking with other networks Study Group 16