DSL is affected by distance. The greater the distance between your installation and the telephone company's Central Office (CO), the lower your speeds will be. In other words, if your home or small business is close enough to the telephone company's central office that offers DSL service, you can receive downstream data rates at up to 1.5 Mbps. That means you can download files very fast, much faster than you probably are now achieving with an ordinary 56K modem. Picture it as a continuous, uninterrupted transmission of motion video, audio, voice, and even multimedia 3-D effects. If you want to upload, your speed will be a little less (speeds can range from 640Kbps to 1Mbps), but still will be remarkably faster than when using a 56K modem.
A DSL line carries both data and voice signals on the same line. And the data part of the line is always connected. So, you can speak on the phone and use the Internet at the same time. Sometimes, a splitter is required.
It's predicted that DSL will replace Integrated Services Digital Network (ISDN) in many areas in the near future. It will also replace or be a better option than the cable modem currently available for bringing multimedia and 3-D effects to homes and small businesses.