GENEVA -- The International Telecommunication Union today reached agreement on a new global standard for Single pair High bit-rate Digital Subscriber Line (SHDSL)transceivers, which will allow network operators to economically and efficiently offer leased-line services to business customers using existing copper loops. SHDSLenables data, voice and video to be transmitted over distances never before attainable by other flavours of symmetric DSL technology.

The approved standard, designated ITU-T Recommendation G.991.2, is effective immediately.

"This latest Digital Subscriber Line (DSL) standard complements ITU-T’s series of ADSL (asymmetric DSL) standards in that it provides symmetrical high bit ratenetwork access, and thus is particularly attractive to business customers fulfilling their needs to upload and exchange large amounts of data", said Peter Wery,chairman of ITU-T Study Group 15.

SHDSL enables operators to provide symmetric, high-speed data transmission over the existing copper pairs without requiring the installation of additional cable. It is amulti-rate DSL technology that allows data rates from 192 kbit/s to 2 312 kbit/s and can transport T1 (1 544 kbit/s), E1 (2 048 kbit/s), ISDN, ATM and IP signals. Theframing to support these various types of signals is negotiated at start-up using the ‘handshaking’ protocol defined in ITU-T Recommendation G.994.1.

This new standard has strong commonality with regional standards and has been designed to prevent interference to other DSL systems operating in the same cable.

A number of enhanced ADSL Recommendations on high-speed network access were also approved, covering:

Method for DSL systems to negotiate mutually supported operating modes (G.994.1)
Reference architecture for ADSL systems (G.995.1)
Test methods for ADSL systems (G.996.1)
Management of ADSL systems (G.997.1)
ITU also approved today the first of a set of standards for Home Phone-line Networking transceivers, ITU-T Recommendation G.989.1. This will allow home-networkingdevices (e.g. computer peripherals) to operate over existing telephone wiring.

http://www.itu.int/newsroom/press/releases/2001/02.html