Microsoft Lync Server (previously Microsoft Office Communications Server OCS and Microsoft Live Communication Server LCS) 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 3rd 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.
- 2013 – Microsoft Lync Server 2013
- 2010 – Microsoft Lync Server 2010
- 2009 – Office Communications Server 2007 R2
- 2007 – Office Communications Server 2007
- 2006 – Live Communications Server 2005 with SP1
- 2005 – Live Communications Server 2005, codenamed Vienna
- 2003 – Live Communications Server 2003
Client software and devices
Microsoft Lync is the primary client application released with Lync Server. This client is used for IM, presence, voice and video calls, desktop sharing, file transfer and ad hoc conferences. Microsoft also ships the Microsoft Attendant Console. This is a version of the Lync more oriented towards receptionists or delegates / secretaries or others who get a large volume of inbound calls.
Other client software and devices include:
- Lync Communicator Mobile is a Mobile edition of the Lync Server 2010 client and designed to offer similar functionality including voice calls, instant messaging, presence and single number reachability. Clients for all major platforms including the IPhone are being developed
- Lync Communicator Web Access is a web instant messaging and presence client. This version works as well on IE, Firefox and Opera browsers.
- Microsoft RoundTable is an audio and video conferencing device that provides a 360-degree view of the conference room and tracks the various speakers. This device is now produced and sold via Polycom under the product name CX5000.
- LG-Nortel and Polycom also make IP phones in a traditional phone form factor that operate an embedded edition of Office Communicator 2007. The physical plastic phones as referred by Microsoft are also named Tanjay Phones.
One basic use of Lync Server is instant messaging and presence within a single organization. This includes support for rich presence information, file transfer, instant messaging as well as voice and video communication. (These latter features are often not possible even within a single organization using public IM clients, due to the effects of negotiating the corporate firewall and network address translation). Lync uses Interactive Connectivity Establishment for NAT traversal and TLS encryption to enable secure voice and video both inside and outside the corporate network.
Lync Server also supports remote users, both corporate users on the internet (e.g. mobile or home workers) as well as users in partner companies. Lync supports “federation” – enabling interoperability with other corporate IM networks. Federation can be configured either manually (where each partner manually configures the relevant edge servers in the other organization) or automatically (using the appropriate SRV records in the DNS).
Microsoft Lync Server uses Session Initiation Protocol (SIP) for signaling along with the SIMPLE extensions to SIP for IM and presence. Media is transferred using RTP/SRTP. The Live Meeting client uses PSOM to download meeting content. The Communicator client also uses HTTPS to connect with the web components server to download address books, expand distribution lists, etc. By default, Office Communications Server encrypts all signaling and media traffic using SIP over TLSand SRTP. There is one exception to this – traffic between the Mediation Server and a basic media gateway is carried as SIP over TCP and RTP. However, if a hybrid gateway is leveraged, such as one from Microsoft’s Open Interoperability Site, then in fact everything is encrypted from all points if (SSL certificates are configured on the gateway and TLS elected as the transmission type).
IM is only one portion of the Lync suite. The other major components are VOIP telephony and video conferencing through the desktop communicator client. Remote access is possible using mobile and web clients.
Several third parties have incorporated Lync functionality on existing platforms. HP has implemented OCS on their Halo video conferencing platform.
Microsoft released Microsoft Office Communications Server 2007 R2 in February 2009. The R2 release added the following features
- Dial-in audio conferencing
- Desktop sharing
- Persistent Group Chat
- Attendant console and delegation
- Session Initiation Protocol trunking
- Mobility and single-number reach