Patent ID: 7694127

Claim:
A method for transferring multimedia information over Internet protocol (IP) between a private client in a private address space created by a Network Address Translation (NAT)/firewall device and a remote client in an outside address space separate from the private address space, said method comprising: establishing a persistent registration connection between the private client and a traversal server in the outside address space, the persistent registration connection passing through the NAT/firewall device; registering with a standard communication registration server in the outside address space for multimedia information transfer with the private client; generating, at the traversal server, a probe definition that uniquely identifies a connection establishment event; sending a standard message according to a Session Initiation Protocol (SIP) for real-time multimedia communication from the traversal server to the private client, the standard message including the probe definition, the sending including receiving a standard SIP INVITE message at the traversal server from the private client via the persistent registration connection, the standard SIP INVITE message including at least one of a contact header and a record route header having an address of the private client, modifying at least one of the contact header or the record route header to include an address of the traversal server, forwarding the standard SIP INVITE message from the traversal server to a SIP registrar/proxy including at least one of a modified contact header and a modified record route header, receiving a standard SIP OK message at the traversal server from the remote client via the SIP registrar/proxy, adding a standard SDP parameter to the standard SIP OK message at the traversal server, adding the probe definition to the standard SIP OK message at the traversal server, the probe definition having been determined by the traversal server, and forwarding the standard SIP OK message including an added SDP parameter and an added probe definition to the private client; receiving a probe packet including a probe based on the probe definition at the traversal server from the private client, a source address of the probe packet having been translated by the NAT/firewall device; and transferring the multimedia information between the private client and the remote client through the NAT/firewall device over IP using the source address of the probe packet.