Microsoft plans to shut down 15-year-old MSN Messenger for good this autumn.

MSN Messenger is a well-known instant messaging client by Microsoft (rebranded as Windows Live Messenger in 2005). Even though the client supposedly had over 330 million monthly active users each month just four years ago, Microsoft has announced it will switch off the service and transfer any remaining users to Skype by 31 October, according to the BBC and several Chinese newspapers.

After acquiring Skype, Microsoft announced a couple years ago that the MSN Messenger and Skype services would merge. All users of MSN Messenger would move to Skype, with the exception of those living in mainland China. Although the rest of the world hasn't been able to sign into the client since March 2013, it appears users in China will no longer have access in a few short months.

Skype recently claimed it had over 80 million concurrent users online, most of which were likely making use of the service's popular voice and video call features. With the rise of Skype, Microsoft has reportedly begun emailing Chiners users on 28 August about an immenent shut down of MSN Messenger. Microsoft also offered them free credit should they migrate to Skype.

READ: Skype makes group video calls free

That said, with ephemeral messaging apps - such as Yo and Snapchat - being all the rage at the moment, one could also speculate whether the writing is already on the wall for Skype. It's a popular client now, but will it still be in another few years?

It's not clear why Microsoft decided to completely shut down MSN Messenger, as it is colloquially referred to by old and existing users, but having a new chief executive officer at the company's helm might have something to do with it.