IAX is the native Asterisk PBX server to server communications protocol designed to work well across firewalls and NAT.
Multiple IAX trunks can be configured for call routing. IAX trunks can be configured as providers, or as peers registering with providers.
IAX supports multiplexing of channels over a single link. Data from multiple calls are merged into a single stream between two endpoints, reducing the IP overhead without creating additional latency.
If the Com.X is located behind a NAT/firewall on the network, configure the NAT/firewall to forward UDP port 4569 to the Com.X internal IP address.