A quick but important reminder for those deployments upgrading their user clients from Office Communicator 2005 to Office Communicator 2007 or 2007 R2.
When an OCS user gets enabled for Enhanced Presence, either through the OCS management console or programmatically (through a script modifying AD directly or the WMI provider), Communicator 2005 users can still login. However, when the user signs-in for the first time with a newer Office Communicator client (such as 2007, 2007 R2, or even the R2 version of Communicator Web Access), there is no going back – the user will not be able to sign-in again with Communicator 2005. The “RichMode” value gets set to ‘true’ for that user in the OCS backend database when a newer client is used for the first time.
The Enhanced Presence status for a particular user can be seen in the OCS management console in the user properties (“Other settings” in the User properties in R2, or the Communications tab | Configure button” in the Active Directory snap-in).
For more information about modifying the AD user property to enable Enhanced Presence programmatically see my previous blog entry “Provisioning OCS Users (and the AD msRTCSIP-OptionFlags Attribute)”.
A good explanation of the different stages of Enhanced Presence is available here on the Office Communicator team blog.
[...] CWA users must be enabled for Enhanced Presence to login using CWA R2. If they are not, the user will be prompted multiple times to authenticate and then be shown an error message. If there are Office Communicator 2005 clients still deployed, there are implications enabling Enhanced Presence (see previous blog entry Enhanced Presence and Upgrading Communicator Clients). [...]