Reports suggest the firm will start winding down service from March, but will not be switching it off completely for another 12 months.
Microsoft is to start winding down its Windows Messenger service from 15 March, but the network will remain available to users in some form for the next 12 months.
On 8 January, The Next Web reprinted an email sent from Microsoft to Messenger users explaining they would be migrated over to Skype, which was acquired by the Redmond giant in 2011.
The service is understood to have more than 100 million users.
“On 15th March 2013 we are retiring the existing Messenger service globally...and bringing the great features of Messenger and Skype together," the email stated.
"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’s move towards a consolidated communication service is a necessary development
However, Ars Technica has since revealed that 15 March is just the start of the retirement process, not a definite end date for the service.
On 15 March, the Messenger client program will cease to connect to the Messenger network. Anyone trying to log in via the client will be asked to install Skype.
In October this year, Microsoft will turn off support for third-party clients using the open XMPP protocol introduced in December 2011, which includes Digsby, Adium and Pidgin.
However, the Messenger network will function until March 2014, meaning the current Windows Phone and Xbox Messenger clients will continue to work for another 16 months.
What is not yet clear is how this gradual switchover will affect the Messenger client that comes bundled with Windows 8, a prominent feature of the Modern UI default Start screen.
Randy Roberts, VP of mobility products at Siemens Enterprise Communications, said he was not surprised Microsoft had decided to retire its 14-year-old messaging product.
“We live in a world where being contacted via social media, email, IM, SMS and phone calls all in the same day is common place," he said.
"Microsoft’s move towards a consolidated communication service is a necessary development to try and keep a population that is constantly on the move connected,” Roberts added.