Messenger was retired in April 2013 and is no longer available or supported on most Mac and Windows operating systems. *
You can continue to make audio and video calls with your contacts on Skype and Facebook and send IMs for free—your contacts will come with you when you update to Skype and sign in with your Microsoft account.
For information about moving from Messenger to Skype, visit the About Skype page.
To learn about instant messaging with Skype on your Windows desktop, visit the Skype instant messaging page.
To find out how to call your contacts with Skype on your Windows desktop, visit the Skype–to–Skype calling page.
* If you have a Mac operating system earlier than OSX or a Windows operating system earlier than Windows XP, you won't be able to update to Skype. Messenger will continue to be available on these operating systems until it is discontinued later in 2013.