Windows XP Professional comes with inbuilt installed Telnet Client. Where if you use Vista or Windows 7 it will not allow you to access telnet. You need to make Telnet Client Feature on From Control Panel.
You can go through following steps for using Telnet Client.
For Windows Vista/Windows 7
- Click Start, and then click Control Panel.
- On the Control Panel Home page, click Programs.
- In the Programs and Features section, click Turn Windows features on or off.
- If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
- In the Windows Features list, select Telnet Client, and then click OK.
For Windows Server 2008/ Windows Server 2008 R2
- Start Server Manager. To do so Click Start, right-click Computer, and then click Manage.
- If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
- In the Features Summary section, click Add features.
- In the Add Features Wizard, select Telnet Client, and then click Next.
- On the Confirm Installation Options page, click Install.
- When installation finishes, on the Installation Results page, click Close.