Recommendation G.99 1.2 describes a transmission method for data transport in telecommunications access networks. SHDSL transceivers are designed primarily for duplex operation over mixed gauge two-wire twisted metallic pairs. Optional multi-pair operation is supported for extended reach applications. Optional signal regenerators for both single-pair and multi-pair operation are specified, as well. SHDSL transceivers are capable of supporting selected symmetric user data rates in the range of 192 kbiîís to 2 3 12 kbiîís using a Trellis Coded Pulse Amplitude Modulation (TC-PAM) line code. Optional extensions described in Annex F allow user data rates up to 5696 kbit/s. SHDSL transceivers are designed to be spectrally compatible with other transmission technologies deployed in the access network, including other DSL technologies. SHDSL transceivers do not support the use of analogue splitting technology for coexistence with either POTS or ISDN. Regional requirements, including both operational differences and performance requirements, are specified in Annexes A, B and C. Requirements for signal regenerators are specified in Annex D. Annex E describes application-specific framing modes that may be supported by SHDSL transceivers.