By operating in a frequency range above POTS, digital subscriber line technology, known generically as xDSL, delivers multimegabit data bandwidth with simultaneous POTS service over those same copper wires. Installing an xDSL modem requires support of the local telephone company. Even though it uses the existing wiring, the line must be prepared by removing any phone company equipment that can impair data transmission. There are many forms of xDSL technology. DSL modems, with a bidirectional throughput of 160Kbps, are used to deliver ISDN with a basic access rate of 128Kbps and a maximum range of about 5.5 kilometers over a single twisted-pair.
Many experts believe that ADSL is likely to dominate in the long run.
It offers the maximum throughput over the greatest distances, plus it's simple, easy to deploy, and cheap, because most applications are suited to asymmetric data transmission, such as browsing, home shopping, remote LAN access, and video on demand. Look for xDSL technologies, and ADSL in particular, to be deployed rapidly as telephone companies complete their technical and market trials and race with cable and wireless service provider s to offer affordable multimegabit data services. Steve Klingler is president of Programming Solutions Inc. in Salt Lake City.