Servus

C:\Program Files\Microsoft Office Communications Server 2007\Server\Core>abserver -regenUR
Wait 5 minutes and then run the same command with the -SyncNow switch
On the client, close Office Communicator, and delete GALContacts.db (found in the user’s profile directory under Local Settings\Application Data\Microsoft\Communicator) and then restart the client.

Using my previous employers standard SQL build caused some issues installing a new OCS pool. The 2 errors are related to the articles below.
Security Account Delegation
http://msdn.microsoft.com/en-us/library/aa905162%28SQL.80%29.aspx
Shrinking your model DB size.
http://support.microsoft.com/default.aspx/kb/307487

The OCS 2007 Client Version filter can be a bit confusing as to how to filter clients. I’ve run into this issue twice now, so I thought I’d share my experience and dive into this a little deeper. TechNet has an explanation of how to configure the Client Version filter, but there are quite [...]

There is some debate in the industry about bandwidth requirements for Microsoft’s RTAudio and RTVideo codec used in Office Communication Server 2007. This is a very good description of the actually requirements for planning purposes.
The short answer is that you should plan 57 Kbps for Audio and 320 Kbps for Video. The QoE [...]

Office Communication Server 2007 has a number of port requirements that are specific to the feature that you will be deploying. The following diagram breaks out the required ports based on the server role you are deploying.