The most common dial-up connection is made by using a standard analog telephone line and a modem. Standard analog phone lines are available worldwide and meet most requirements of a mobile user. Standard analog phone lines are also called PSTN (public switched telephone network) or POTS (plain old telephone service).

Hundreds of modems are compatible with Windows XP. Most modems that comply with industry standards should interoperate. However, many difficult-to-detect problems are the result of incompatible modems. To find hardware that is supported by Windows operating systems, visit the Windows Catalog on the Microsoft Web site.

Modems are automatically detected. This is especially useful for users who are not sure what modem is installed (for example, an internal modem). You can use shared modem pools for dial-up connections. Modem data compression and error control are available on most modems. However, built-in software compression offers enhanced