During a migration from Live Communications Server 2005 with SP1 to Office Communications Server 2007 R2, users are re-homed on Office Communications Server 2007 R2 servers so that they have access to new features and capabilities. Users do not need to update their clients before they are re-homed on the new servers. However, Office Communicator 2005 users will operate in legacy mode until they are switched to rich presence mode, after which they can use Office Communicator 2007 R2, Microsoft Office Communicator Web Access 2007 R2, and telephony devices that provide rich presence capabilities.

Audio and video interoperability with Office Communicator 2005 is not supported in Office Communicator 2007 R2.

To access new features and capabilities, Office Communicator 2007 R2 users must be homed on Office Communications Server 2007 R2. When you update from Office Communications Server 2007, you can update clients to Communicator 2007 R2 by using managed installation software (such as, Microsoft Systems Management Server 2003), a Group Policy object, or Windows logon scripts.

Moving users from Office Communications Server 2007 to Office Communications Server 2007 R2 involves re-homing users on the new servers. However, clients are not required to be upgraded in advance before they are re-homed on new servers, so the process of updating clients can be phased over time.

To enforce the use of Communicator 2007 R2, you can use the client version control feature in Office Communications Server 2007.

Note:
In Office Communications Server 2007, if you configured the media port range registry key settings to reduce the ports that can be used for media, the recommendations have changed. For details about the port recommendations, see Media Port Range Registry Keys.

After a Communicator user upgrades to Communicator 2007 R2, the Call Forwarding settings in earlier versions of Communicator may become unavailable. For example, if the user has already upgraded Communicator on one computer and then signs in to an earlier version of Communicator on another computer, the user may be unable to change some or all of the Call Forwarding settings. The user should upgrade all instances of Communicator or sign in to the Communicator 2007 R2 version to change Call Forwarding settings.

For details about the additions, changes, and deletions to Group Policies for Communicator 2007 R2, see Office Communicator 2007 R2 Group Policy Settings.