Retrieving Address and Port Information
The IRTCClient::NetworkAddresses method returns the address and port used to establish point-to-point communication sessions.
If the client is behind a NAT or firewall, the NetworkAddresses method determines the port and address on the NAT or firewall that is used for the session.
When a client calls NetworkAddresses with the fExternal parameter set to TRUE, the method returns the external address and dynamic port on the NAT. The client can communicate this address out-of-band to the called party to establish point-to-point sessions.
If a client is behind a NAT without UPnP IGD DCP support or a firewall, point-to-point communications are not possible without an application-level gateway.