Windows Live Messenger, used by around 300 million people each month, is to be retired on March 15th 2013. In an email to all users, Microsoft said on that date Messenger log-ins will no longer work and users must turn to Skype.
The email also encouraged users to update to Skype and familiarise themselves with the service before the switch-off. Microsoft acquired Skype in October 2011 for $8.5bn.
To help people migrate before 15 March, Microsoft has added an upgrade button to its desktop Messenger that when clicked uninstalls Messenger and puts Skype in its place.
China is the only country in which Messenger will keep operating as it is run under licence there.