Microsoft started sending out emails to Windows Live Messenger users to inform them that Windows Live Messenger would be retired on March 15 and all the users will be migrated to Skype.
But there are a lot of third-party clients such as Pidgin, Adium, Digsby, and Trillian which use Microsoft'sMSP and XMPP messaging protocols to connect to the Messenger service for allowing users to chat with Windows Live Messenger users. If Microsoft were truly to retire the Messenger service on March 15th, all these clients would instantly cease working.
Asrtechnica asked Microsoft that what would happen to these various clients. The company tells them that contrary to the previous reports, the Messenger service isn't being retired on March 15th. That date does represent the start of the transition away from Messenger, but the service is set to operate for some time yet.
On March 15th, the Windows Messenger client will be blacklisted and unable to connect to the network, informing users that they must install the Skype client instead. The Skype client will continue to connect to the Messenger network (as it does presently) and will allow communication with Messenger users.
Other clients, however, should be unaffected and will continue to connect just fine. In October 2013, Microsoft will turn off its XMPP support. Third-party clients depending on this protocol will stop working at this time. The network itself will continue running until March 2014. At this point, MSP support will be turned off, and it's likely that the current Windows Phone and Xbox clients will at this point stop working.