Microsoft’s long time popular instant messaging client, Windows Live Messenger is going to be retired/killed off in favour of recently aquired Skype.

Microsoft has officially confirmed that the company will discontinue Windows Live Messenger in 2013, moving all users over to Skype early in the new year. This move will include migrating Messenger’s existing 100 million users over to Skype’s platform.

Skype accounts are already linked to Microsoft Accounts and users are currently greeted with the option to log into Skype using their Microsoft or Facebook accounts.

“We will retire Messenger in all countries worldwide in the first quarter of 2013” said Skype’s Tony Bates.

To entice Windows Live Messenger users to switch services and not abandon it altogether, Microsoft explains that Skype offers features like broader device support for all platforms, including iPad and Android tablets;  IM, video, and calling landlines and mobiles all in one place; sharing screens; video calling on mobile phone; video calling with Facebook friends; and group video calling.

Users will also notice that Skype is a freemium model (and not ad-based), which in addition to simply consolidating the services is likely part of this strategy for Microsoft.