ITU-T Recommendations

Voice-band data traffic has traditionally been transported by circuit switched systems and equipment. With the advent of the networks optimized for the transport of Internet Protocol (IP), and as a result of its considerable growth and pervasive nature, more and more voice-band data traffic is expected to be carried over IP networks.Given that voice and voice-band data services remain a significant part of telecommunications, there is a need to ensure a high quality of service for voice and voice-band data carried in part, or wholly, via IP. This Recommendation defines procedures for equipment that interconnect GSTN networks with IP networks to provide satisfactory, transparent delivery of modulated voice-band data (VBD) as encoded audio content over IP (data modems, facsimile terminals and text telephones).This Recommendation is complementary to the modem relay and voice-band data ITU-T Recs V.150.0 and V.150.1.Corrigendum 1 (09/2005) contains clarification to clauses 7.1 and 7.1.1.This corrigendum adds clarifications to the Recommendation in terms of the scope of the use and control of echo cancellers and the application of RFC 2833 with VBD.