Using Windows Live Messenger you can sign in to Windows Live Messenger on multiple devices or computers at the same time.

That means, if you're already signed in to Messenger on a computer, you can sign in on  on another computer without having to sign out on the first computer. You can also sign in to Messenger on your computer and on the web or any other devices like Windows Mobile at the same time.

 

Notes

• If you receive a message while you're signed in on multiple devices, the message will appear on each device that you're signed in on. Also, if you perform an action on one device, such as open or close a conversation window, the action will occur on all devices.
• If you sign in to a version of Messenger that doesn't support the multiple sign-in feature, you will automatically be signed out from the other devices.