Patent ID: 7664096

Claim:
An Internet Protocol (IP) phone with an assigned phone number capable of communicating over a packet-based communication protocol, the IP phone located behind a firewall, the IP phone comprising: a Dynamic Host Configuration Protocol (DHCP) client to, upon an initial power up of the IP phone, communicate with the firewall to receive an IP address; an IP agent to, upon receiving the IP address from the firewall, register with a domain name system (DNS) switch based upon at least the following parameters: the assigned phone number, the received IP address, a public IP address associated with the firewall, and a medium access control (MAC) address associated with the IP phone; and wherein, upon successful registration with the DNS switch, the IP agent is to receive a port number and address over which future communications are to be performed, and the IP agent is to monitor for changes to the public IP address associated with the firewall after the IP phone is registered with the DNS switch and, upon detecting a change to the public IP address associated with the firewall, the IP agent is to identify a new public IP address associated with the firewall and reregister with the DNS switch without reinitializing the IP phone based upon at least the following parameters: the assigned phone number, the received IP address, the identified new public IP address associated with the firewall, and the MAC address associated with the IP phone.