This is a rather confusing event. It occurs on the Exchange server 2010 that is holding the Unified Messaging role. “The following UM IP gateways did not respond as expected to a SIP OPTIONS request”, and at the end “This operation has timed out”. The server mentioned in the erro is, in this senario, the Lync server.

I thought I knew this PKI stuff and I was sure that all my certificates where correct. Also when telneting for the exchange server to the Lync server on port 5061 there was most defiantly an answer – No timeout”. After a while a decided to do all my certificates all over. Replacing the Lync ,  of course made no difference. When replacing the exchange certificate I change the SN to be the FQDN of the server, This did the trick. The error message disappeared. So now I remember that on Exchange UM server keep FQDN as Subject name and place all other names as SAN’s