Network Know-How

Connections Through a Telephone Line

When a high-speed wide area network service such as DSL is not available, you can connect your computer or LAN to the Internet, or directly to a remote computer, through the dial telephone system (the Public Telephone Switched Network or PTSN, also known as POTS, short for Plain Old Telephone Service). Dial-up network links are considerably slower than DSL, cable, or other high-speed services, but they're convenient because there's a POTS telephone line in just about every home and business, and because the PTSN often continues to work during power failures.

A network connection through a telephone line uses a modem to convert digital computer data to sounds that can pass through the PTSN. A second modem at ...