I am setting up a new CUCM7 environment which will be shared by various divisions of the Company. As such the Server environment is in a DMZ. We are trying to place the Gateways inside the firewalls (on the same networks as the phones) and have created a rule to allow all traffic bi-directionally between the Gateways, our Publisher and 2 Subscribers. For some reason we cannot get the gateways to register via MGCP. I do not see any traffic being blocked in the firewall log, and have placed a sniffer on the segment of the gateway and servers. The Sniffer trace on the server side shows an MGCP request initiated by the gateway to each of the subscribers, as well as a response from the servers. On the Client side, we cannot see the response. I have as a test placed a gateway in the same network as the servers, I can place a call from a phone registered to that gateway from inside our network, and can hear voice initiated from that phone, but cannot recieve voice from the far end phone. It seems like there is a problem with UDP, but where?