Microsoft's Messenger service is coming to an end. In the first quarter of 2013, Messenger will no longer be available as a separate service in all regions except mainland China, the company announced this week.Microsoft is folding Messenger into its Skype voice-over-IP service, according to an announcement made on Tuesday.Within Skype, there's currently a Messenger-like user interface available to carry out instant messaging, along with voice calls. To aid the shift, Microsoft is assuring Messenger users that they can get their contacts automatically populated into Skype. Those who already have both Messenger and Skype accounts can merge them via the Skype signup process, available here.Current Messenger users who want to continue to use Microsoft's instant messaging service have to get the current version of Skype, which requires the use of a "Microsoft account" signup.Microsoft account is the new name for Microsoft's Windows Live ID. That ID is used for consumer applications such as Microsoft's Hotmail (now Outlook.com), SkyDrive and Messenger services, among others. If a Windows Live ID user had used an e-mail address and password as the basis of their Windows Live ID, then they also "already have a Microsoft account," according to a Microsoft description.The Microsoft account is more than just a name change for Windows Live ID. A Microsoft account shares information across Microsoft's services. In May, Chris Jones, vice president of the Windows Live Group at Microsoft, explained that with a Microsoft account, "your contact list is shared across Windows Phone, Windows 8, Hotmail, Messenger, and SkyDrive, so when you add a contact in one place, it shows up in the cloud and on all of your other devices and services." Similarly, if a user connects their Facebook, LinkedIn or Twitter accounts with their Microsoft account, then those contacts will show up across Microsoft services.Microsoft's commercial-grade instant messaging service is available as a pop-up option when users hover their mouse cursors over an e-mail sender's name in the Outlook 2010 e-mail client. Other instant messaging options for businesses include using the Microsoft Office Communicator client in conjunction with Microsoft Office Communications Server 2007. The Lync client can also be used for instant messaging by Microsoft's business customers via Lync Server 2010 or the hosted Lync Online service offered via Office 365. Lync Server 2010 is the successor product to Office Communications Server 2007 R2.