SAN FRANCISCO - Microsoft on Wednesday announced that its instant messaging service Messenger will be officially shut down on March 15, reminding users to move to Skype, the real-time Internet communication service it bought in 2011.

In an email to users titled "Important info about your Messenger account," Microsoft said Messenger's more than 100 million users can migrate to Skype by signing in with their Microsoft accounts and enjoy features like instant messaging, video calling on cell phones and screen sharing.

Microsoft acquired the VoIP (voice over Internet Protocol) service Skype in May 2011 for 8.5 billion U.S. dollars and planned to gradually merge it into its every product, like Xbox and Windows Phone.

Last November, the software giant announced it will move Messenger's users to Skype in the first quarter of 2013 with the exception of Chinese mainland where Messenger will continue to be available.

Microsoft's Messenger service is often referred as "MSN" as it was first launched as "MSN messenger" in 1999.

In June 2009, on the 10th anniversary of Messenger's release, Microsoft said the service attracted over 330 million active users each month worldwide.