Patent ID: 7764640

Claim:
A method for supporting Internet Protocol (IP) mobility of a Mobile Node (MN) in a mobile communication system supporting Mobile IP (MIP) and Session Initiation Protocol (SIP), comprising: performing an initial MIP location registration in a Home Agent (HA) of a home network through a first Foreign Agent (FA) of a first foreign network in which the MN is located; sending, to a Correspondent Node (CN), a SIP response OK message in which a home address of the MN is recorded when the MN receives a SIP invite message from the CN; sending, by the CN, a packet to the home address of the MN in a state in which a SIP call of the MN is established; and performing a MIP location registration in the HA through a second FA without a SIP location registration when the MN moves to a second foreign network during the SIP call, wherein the home address indicates a unique IP address assigned by the home network.