I have several offices which connect to the central site with either point to point T1's, or 12Mb DS3's. A DMVPN solution has been installed as a failover from the main circuits. When the main circuit fails, phones fail to register with UCM 5.13 located at the hub site. It appears that sccp port 2000 does not arrive at the UCM cluster, but appears to stop at the hub side of the tunnel. As a result, phones do not register or register but fail to SRST fallback mode. As a result, internal dialing is not available, since the gateway router now sees itself as an autonomous system.
Anyone ever seen this type of condition? I've bee researching this issue for months, but with no solution. I've placed a sniffer on the hub side of the connection, but port 2000 packets are never seen. Thanks.