Topic Last Modified: 2011-05-12

Microsoft Lync Server 2010 has replaced Communicator Web Access with a new Microsoft Silverlight-based client called Microsoft Lync Web App. Depending on the requirements of your organization, you have several options available for migrating Communicator Web Access functionality to Lync Server 2010.

Lync Server 2010 only deployment—IM and presence is not required for Reach scenarios: You do not need to perform any additional migration steps.

IM and Presence is required for Reach scenarios: Lync Web App does not support instant messaging (IM) and presence. If this is a requirement of your organization, you must also maintain a deployed instance of the previous version of Communicator Web Access in your environment. Because Communicator Web Access can point to a Lync Server pool as a next hop, there is no need to maintain a separate Office Communications Server pool.

Side-by-Side deployment: If you maintain an Office Communications Server pool deployed alongside a Lync Server pool, the user experience will vary depending on which server the user is homed to and which pool Communicator Web Access is pointing to.

If you are going to maintain an instance of the previous version of Communicator Web Access, you need to point Communicator Web Access to the Lync Server pool. For details, see Repoint Communicator Web Access to Lync Server 2010 (Office Communications Server) .

Note:
When Communicator Web Access is deployed, all users who sign in through Communicator Web Access have support for IM and presence. It does not matter if they are homed in the Office Communications Server pool or the Lync Server pool.

Deployment Scenarios

If a deployment contains a Communicator Web Access server, then all users can access IM and presence functionality irrespective of the following conditions:

Whether users are homed in an Office Communications Server pool or Lync Server pool
Whether the Communicator Web Access server is pointed to Office Communications Server or Lync Server

The following table describes the behavior for the various deployment scenarios and end user experience.

Scenario	Behavior
All users are homed in the Lync Server pool Communicator Web Access is pointed to the Lync Server pool	All users will have support for IM and presence through Communicator Web Access and meetings though Lync Web App.
All users are homed in the Lync Server pool Communicator Web Access is pointed to the Office Communications Server pool	All users will have support for IM and presence through Communicator Web Access and meetings through Lync Web App.
Users are split between the Lync Server and the Office Communications Server pools Communicator Web Access is pointed to the Office Communications Server 2007 pool.	Lync Server homed users will have support for IM and presence through Communicator Web Access. These users will use the Lync Web App for meeting access. Office Communications Server homed users will have support for IM and presence using Communicator Web Access as long as Office Communications Server pool is running. These users will use Communicator Web Access for meetings hosted on Office Communications Server. They can also join meetings hosted on Lync Server by using Lync Web App.
Users are split between the Lync Server and the Office Communications Server pools Communicator Web Access is pointed to the Lync Server pool.	Lync Server homed users will have Reach IM and presence support using Communicator Web Access as long as the Lync Server pool is running and will have meeting through Lync Web App. Office Communications Server homed used will have both IM and presence and meeting support using Communicator Web Access. If the user has migrated and joins or creates a new conference using Meet Now (Join Launcher link), the user will join the meeting using Lync 2010 Reach. If the user has not migrated, the new conference will be created on the Office Communications Server 2007 pool and the user will use Communicator Web Access to join the conference. If user has not migrated, the user can join a conference created on Lync Server 2010 by using the Reach Join Launcher link.