Microsoft Lync Server (previously Microsoft Office Communications Server) is an enterprise real-time communications server, providing the infrastructure for enterprise instant messaging, presence, file transfer, peer-to-peer and multiparty voice and video calling, ad hoc and structured conferences (audio, video and web) and, through a third-party gateway or SIP trunk, PSTN connectivity. These features are available within an organization, between organizations, and with external users on the public internet, or standard phones, on the PSTN as well as SIP trunking. Microsoft Lync Server 2010 was the first Lync Branded Server and was available generally (GA) in November 2010. Microsoft Lync 2013 is the second release of the software which was Release to Manufacturer (RTM) in October 2012 - with GA still to be confirmed by Microsoft.
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