Does DSL Use Dial-up?

The upload and download speeds of your computer are limited by the hardware that formats the signal and the line that carries the signal. A dial-up connection uses your telephone line the same way your regular telephone uses it. A signal within a certain frequency range is sent down the line. The frequencies that dial-up uses are in the same range as the frequencies used for a phone call, which is why you can't use your phone and your dial-up connection at the same time. DSL connections, though, use a much higher speed.

It doesn't make any sense to make a dial-up modem work any faster than your phone line. That's why dial-up modems top out at about 56 Kbps, which is 55,000 bits per second. Because DSL uses much higher frequencies, the DSL modem has to operate at those higher frequencies. The actual speed of a DSL connection is established by a back-and-forth communication between your modem and the service provider's "central office." So, although both DSL and dial-up service use modems, the hardware is completely different.

Because DSL, dial-up, and your home phone use the same line, you need to have some way to separate their signals. For dial-up and the regular phone, it's easy --- you separate the two by using them at different times. DSL, however, doesn't need to use the line at a separate time, because it uses it on a separate frequency. That's why you will need a splitter installed on your phone line. The splitter is a filter that sends high frequency DSL signals one way and low frequency phone, or dial-up, signals another way. Your service provider will install the splitter.

Imagine there's a big lake between you and someone you want to exchange information with. You could put the information in a submarine and send it under the water to the other side, or you could put the same information in a speedboat that skims along the surface. Your DSL modem is like the speedboat while the regular phone line is the submarine. The lake is your phone line, connecting you and your friend on the other side. Dial-up and your phone both use the submarine, which is why they can't be on at the same time, while DSL skims along. So, although the lake --- the phone line --- is the same, DSL does not use dial-up.