my setup is, Gateway (with SRST) at the remote office with a VPN connection over Internet to the head office. The VPN is establish with CheckPoint NG R55.
When the link is broken (for 1-2 minutes) between the CCM and the Gateway, the gateway don't register with the CCM.
I can reach the gateway and everything works at the branch office. I make a no mgcp/mgcp in the remote gateway and the service goes up.
I don't have this problem if the link goes down more than 10 minutes.