AT&T Intellectual Property I, LP

Steve Mueller

James M Doherty

Thomas Lee Adams

Methods and apparatus for maintaining connectivity with an Internet protocol (IP) phone operating behind a firewall are disclosed. An example method disclosed herein comprises registering the IP phone in response to receiving a first registration request from the IP phone, the first registration request including first registration information, the first registration information including a first public IP address associated with the firewall, storing the first registration information, reregistering the IP phone in response to receiving a second registration request from the IP phone, the second registration request including second registration information, the second registration information including a second public IP address associated with the firewall, the second public IP address different from the first public IP address, and reverting to the stored first registration information to process calls associated with the IP phone.

Methods and apparatus for maintaining connectivity with an internet protocol phone operating behind a firewall

A connection between an external host and a host internal to a network (e.g., VPN or LAN) and located behind a firewall and/or NAT-enabled device is established and maintained. A dynamic DNS server is updated with the remote location (RL) information associated with the internal host. This information includes the dialed number (i.e. the number assigned to the internal host), the physical address of the internal host, the private IP address corresponding to the internal host, the public IP address corresponding to the firewall, and the port on which voice data is to be communicated. Each time the internal host's location changes, a new and updated record is sent to the dynamic DNS server. The call placed by an external host reaches its final destination based on the record information in the DNS server table. Once the connection between the external host and the internal host is established, voice traffic is 'cut-through' the firewall on this channel associate with the port designated by the RL record.

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Austin, TX, United States of America

Steve Mueller