A digital subscriber line (DSL) modem is a type of modem used to connect a personal computer (PC) to the Internet. DSL modems can provide for fast Internet access, as they are designed for use with high-speed DSL connections. DSL connections are considered much faster than dial-up Internet connections. In addition to greater speed, DSL service allows the user to talk on the phone while simultaneously accessing the Internet.

A DSL modem, also referred to as an asymmetric DSL (ADSL) modem, provides service that is similar, with the exception of speed, to that provided by a dial-up modem. However, there are some major differences in the setup and technological make up of DSL modems. For example, dial-up modems are frequently, though not always, installed inside computer terminals. By contrast, a DSL modem is typically external and connects to a computer via a USB or Ethernet port.

There are DSL modems that use either a USB or Ethernet port, as well as those designed for use with both. Though a DSL modem may be capable of working with a universal serial bus (USB) port, most experts recommend the use of an Ethernet port. It is said that the connection is considerably better when an Ethernet port is used.

An Ethernet DSL modem can be employed whether the user has a single computer or a network of PCs. A router can be used to allow more than one computer to enjoy the same Internet connection. The router used must be capable of Network Address Translation (NAT). By contrast, USB modems are recommended for use with single computers only. Usually, a modem connected via a USB port cannot support a router.

DSL modems can be purchased from an abundance of electronic, computer, and department stores. They are also available online from a variety of companies, as well as private sellers. Often, they are sold with the required cables, power supply, and filters in one package. Filters included with a DSL modem are called low-pass filters. They are used to keep data signals from causing interference with regular phone calls.

Frequently, companies that provide DSL service offer DSL modems to their customers free of charge. Often, as a condition of receiving a free DSL modem, a customer must sign a contact agreeing to pay for the company’s Internet service for a particular amount of time. In other cases, the DSL modem is purchased directly from the service provider. Some companies offer the modems for rent.