You may have found that the "telnet" command is no longer a part of the DOS command-line interface in later versions of Microsoft Windows, including Vista and Windows 7. The program can be easily added back to the operating system by following the steps below.
1. Open your "Control Panel"
2. Choose "Programs" (Windows 7) or "Programs and Features" (Windows Vista)
3. Choose "Turn Windows Features On or Off" (located in the left column in Windows Vista, or in the main window in Windows 7)
4. Scroll down to "Telnet Client" and make sure the box next to it is checked
5. Click "OK" and wait a few minutes while your computer is updated
6. Close "Control Panel." You should now have telnet available to you.