What is DSL?

DSL is an abbreviation for Digital Subscriber Line technology. DSL refers to the technology used between a customer's premises and the telephone company that enables more bandwidth over the already installed copper cabling than users have traditionally had.

How do analog modems, cable modems, ISDN, and DSL compare?

Analog modems use a telephone network as is. They simply allow digital data to flow over the telephone company's already analog network by performing a digital to analog conversion for transmission onto the network, and vice versa on the receiving end. The only necessity for analog modems is that each end of the call must have a compatible modem. This makes analog modem connections the most ubiquitous form of data communications available today. However, analog modems are thus limited by the telephone company's voice bandwidth service. Current analog modems are struggling to achieve rates of only 56Kbps, whereas the slowest DSL connection is 144Kbps.

Cable modems, although capable of high potential access speeds, also have drawbacks. Primarily, the technology is broadcast-oriented, and the signal is shared between the subscribers in a specific area. The more subscribers in that area, the less bandwidth is available to each. Moreover, cable access is only available in a limited area, and offers the user no choice regarding providers. It is available only through the cable company, which has little experience with Internet services.

ISDN is a telephone company technology that provides digital service typically in increments of 64Kbps channels. A basic rate ISDN line supports two channels, or 128kbps. ISDN has been around for many years, but its popularity is only now beginning to increase due to the limitations of analog modems and the rise of Internet usage. ISDN requires the phone company to install services within their phone switches to support this digitally switched connection service. Roll-out of this service initially got off to a slow start, and was stalled by high costs, lack of standards, and low acceptance rate by consumers.

DSL is technology backed by telephone companies to provide next generation high bandwidth services to the home and business using the existing telephone cabling infrastructure. DSL to the home over existing phone lines currently provides bandwidths up to 1.5Mbps. DSL technologies use a greater range of frequencies over the cable than traditional telephone services, which in turn allow for greater bandwidth with which to send and receive information.