Patent ID: 7623500

Claim:
A method comprising: establishing a secure tunnel between a security gateway in an second network and a mobile terminal located at a first address in a first network, wherein the first network is a public packet network and the second network is a private packet network and the security gateway connects the first network to a second network and the mobile terminal has a second address that identifies the mobile terminal in the second network; in the security gateway, identifying the secure tunnel based on the second address in packets destined for the mobile terminal from the second network detecting a change in the first address of the mobile terminal; in response to the detecting step, sending an update message to the security gateway, wherein the update message includes a new address value of the first address; and wherein the update message also includes data to be transmitted to the security gateway; and based on the update message, updating the first address associated with the secure tunnel; wherein sending comprising creating an update message includes a network address translation discovery payload configured to detect a network address translation device between the mobile terminal and the security gateway.