I recently set up Lync 2010 at our offices and ran into a snag with Exchange 2010 SP2 UM voice mail integration. The symptom was the following error in Exchange 2010 UM:

The following UM IP gateways did not respond as expected to a SIP OPTIONS request.

Additional symptoms were that Lync client are unable to call voice mail and users are unable to leave a message for Lync users.

The Culprit

There are 2 possibilities here…
#1
The UM IP gateway in Exchange 2010 which is set up by running the ExchUCUtil.ps1 script doesn’t have a port listed in the configuration. This can be viewed by running:

Get-UMIPGateway | fl

Resolution

Run Set-UMIPGateway -Port 5061

#2
The certificate assigned to the Exchange UM Server Role was not using its own FQDN as the Subject Name (SN), instead the SN was mail.domain.com. Interestingly this was working perfectly well before when we were on SP1…

Resolution
Re-issued a cert with the FQDN of the UM server as the subject name.