This article relates to Cisco TelePresence Advanced Media Gateway 3610.
Q. When using TLS, calls via the AM gateway either fail to connect, or are dropped after a very short time
On the OCS Gateway VCS, go to VCS Configuration > Calls. Ensure that the Call routed mode is set to Always. This will ensure that the OCS server will only receive SIP signalling from this VCS, which it has configured as a trusted host.