Diary of a Bad Golfer

One thing I ran across recently was when using manual configuration for LCS 2005 the client was able to connect fine, but when using automatic configuration it would return a certificate error.  As you probably know for automatic configuration to work you need a sip.domain.com DNS entry as well as the (for TLS setup) _sipinternaltls SRV record for port 5061.  I had both of these, but was still having an issue - and the problem was something I overlooked.

Our email addresses were not the same as our login domain,  I had both domains specified in the LCS properties for SIP domains, but only had the records created in our logon domain.  After I created the same records in the email domain (as well as requesting the appropriate sip.domain.com certificate and installing it on the server and workstation) I was able to successfully sign in with automatic configuration.