Microsoft Knowledge Base Article 299942 contains the following summary:
This step-by-step guide describes how to enable the Telnet service in Windows 2000.
Telnet is a popular protocol for logging on to remote computers over the Internet. The Telnet server package provides support for remotely logging on to the host computer. To communicate with another host by using the Telnet protocol, you can contact the host by using either the name or the Internet address format (for example, 192.168.1.10). Telnet uses a command-line prompt.