International Telecommunication Union   ITU
 
 
Site Map Contact us Print Version
 Thursday, May 12, 2005

A new ITU-T Recommendation from Study Group 16 aims to support the continued use of modems in IP networks by providing interoperability between products that emulate modem signals. A number of products had emerged to provide this functionality, but no standard solution - until now.

Modem signals have traditionally been transported by circuit switched systems and equipment. As service providers increasingly look towards Internet Protocol (IP) infrastructure, more modem signals will be carried over the protocol. The problem is that the basic design constraints of IP networks do not allow for transparent transport of modem signals (voice-band data (VBD)), hence necessitating special protocols to be run on top of IP to ensure the necessary end-to-end high quality of service.

Many thousands of people still use dial-up (modems) to access the Internet, and so the continued support of modems as many telecommunication service providers move to packet based networks is seen as imperative. Without standards that support their continued use, modem users would suffer from a significantly downgraded experience.

V.152 defines procedures for equipment that interconnect traditional circuit-switched networks with IP networks to provide satisfactory, transparent delivery of modulated VBD as encoded audio content over IP (data modems, facsimile terminals and text telephones). The Recommendation complements the functionality in the modem relay Recommendation V.150.1 (see press release).