I found this little nice tool :)
Debugging Office Communicator 2007 automatic sign-in issues can be frustrating because of the different DNS records and their associated formats that are used to locate the home server or pool to attempt the sign-in. To simplify the debugging process, I wrote a small Windows tool that can be downloaded and run on the client.
The OCS Automatic Sign-In Troubleshooter programmatically performs DNS lookup’s for all the DNS records that the Office Communicator 2007 client uses to locate an OCS 2007 server, and displays the results. The tool performs the DNS queries as the client would (e.g. using the client DNS settings and cache), so that the results will reflect what Office Communicator will use. If people find the tool useful, I will add more functionality.
Additional Details: http://www.insideocs.com/tools/MOCLogin.htm