Topic Last Modified: 2011-01-04

In a coexistence scenario, Microsoft Lync Server 2010 communications software clients can interact with clients from earlier versions of Microsoft Office Communications Server. Users homed on different versions of the server and who are using different clients and client versions can interact as follows:

• When Lync Server 2010 clients interact with Office Communications Server 2007 R2 clients, instant messaging (IM), presence, and voice features are supported.
  
  
• When Lync Server 2010 clients interact with Office Communications Server 2007 clients, IM, presence, and video are supported with some voice feature limitations. For details see Client Interoperability in the Planning documentation.
  
  
• Interaction with Microsoft Office Communicator 2005 clients (basic presence and IM) is supported only if the Office Communicator 2005 user is on a federated network.
  
  

For details about the ability of Lync Server 2010 clients to coexist and interact with clients from earlier versions of Office Communications Server, see Client Interoperability in the Planning documentation.