Patent ID: 8477685

Claim:
A method comprising: assigning, at a first mobile access gateway, a care-of address to a mobile node that is attaching to the first mobile access gateway, the mobile node also having a home address; receiving, at the first mobile access gateway, a packet sent from the mobile node, the packet having a source address and a destination address; receiving, at the first mobile access gateway, a Session Initiation Protocol-related (SIP-related) message from the mobile node, wherein the SIP-related message comprises a session description, and wherein the session description comprises the home address of the mobile node; forwarding the SIP-related message to the destination address, with the home address in the session description replaced by the care-of address assigned to the mobile node when and only when the source address comprises the home address of the mobile node, replacing, at the first mobile access gateway, the source address of the packet with the care-of address assigned to the mobile node, resulting in a modified packet; and transmitting the modified packet to the destination address.