Back in November Microsoft confirmed that moving forward Skype and Messenger were to become one. The shift already started with Skype 6.0 allowing users to log in using Microsoft account credentials, but on March 15 the longstanding instant messaging service will be officially retired.

The compnay this week began emailing its more than 100 million Messenger users, letting them know of the deadline and encouraging them use Skype instead. "Update to Skype and sign in using a Microsoft Account (same as your Messenger ID) and all your Messenger contacts will be at your fingertips," Microsoft said in its message to users. "You'll be able to instant message and video chat with them just like before, and also discover new ways of staying in touch with Skype on your mobile and tablet."

The Messenger service will stop working in all markets except mainland China, as Skype is operated there by a local provider called TOM, The Next Web notes. Those trying to sign in from their desktops after March 15 will see a banner notification asking them to upgrade, which when clicked upon will take them through the Skype installation process and will automatically uninstall Messenger from that machine.

Microsoft acquired Skype back in May 2011 for $8.5 billion. Back then the company wasn't forthcoming about the future of Messenger, but said it planed to integrate Skype across numerous consumer products such as the Xbox 360 and Windows Phone devices. Given the latter's large user base, strong brand in the consumer space, and its presence across mobile platforms, this outcome was just a matter of time.