Patent ID: 8391453

Claim:
A method comprising: receiving, by a firewall and from a private user device, a registration message including a private internet protocol (IP) address associated with the private user device; associating, by the firewall, the private user device with a public IP address and a discrete port number; modifying, by the firewall, the registration message to include the public IP address and the discrete port number; receiving, by the firewall, a call invitation message associated with a public user device, the call invitation message being directed to the public IP address and the discrete port number associated with the private user device; identifying a communications message type to be received from the public user device; determining, by the firewall, whether the call invitation message satisfies a security policy, the call invitation message satisfying the security policy when the communications message type corresponds to one of a plurality of particular communications message types; modifying, by the firewall and when the call invitation message satisfies the security policy, the call invitation message to include the private IP address associated with the private user device; and forwarding the call invitation message to the private user device based on the private IP address associated with the private user device.