Single-Line Digital Subscriber Line

The term Single-Line Digital Subscriber Line (SDSL) has two interpretations. It has been used to describe a proprietary, one-pair, symmetric service using a variety of modulation techniques. It is also the official designation of the ETSI project to develop a standard based on ANSI HDSL-2, but providing variable-rate data, voice, and ISDN without the use of splitters. HDSL-2 is intended to have a single speed in both directions, namely T1. SDSL is expected to be rate adaptable, with a maximum of 2 Mbps.