Telnet is missing from the default install of Windows 7, as it was in Windows Vista. The process, though, to install it is exactly the same as before:
Start by opening Control Panel and then go to Programs and Features
Then once open, down the left-hand side, you’ll see an option Turn Windows Features on or off – go into that.
Then scroll down in the list and check the box next to “Telnet Client” and click OK. Windows will then install telnet, and you’ll be able to run it from a command prompt as normal.
You could, of course, download PuTTY and use that instead of the Windows version of telnet, and benefit from a wide range of additional features.