We are in the process of designing a VOIP infrastructure spanning multiple independent organizations in which many phones reside behind routers performing NAT. Currently, our CCMs reside at two Network Operation Centers outside the NAT domains. The problem we forsee is that when a phone registers with the CCM, it will register with its private IP address, not the global address which is reachable to devices outside the domain. I see there is support within IOS to intercept CallManager registrations and replace the registering IP address with a global, but doing so will break communication between VOIP phones within each NAT domain. Has anyone encountered this before? Thanks in advance.
