Ip handoff process method and system for connection of internet protocols between mobile agents in heterogeneous network

An IP handoff processing method and a system for connection of plural IPs between MAs in heterogeneous networks are provided to offer seamless handoff even in a use of plural IP addresses or different types of IP signal protocols when an MN(Mobile Node) or a mobile network moves to an external network to change an IP address. An IP(Internet Protocol) handoff processing method comprises the following steps of: receiving a registration request message from an MA3(Mobile Agent3)(701); determining whether the registration request message is the content of plural IP handoff registration requests of an MS(Mobile Station)(702); checking whether the entry of the MS is in a visitor list(703); updating the entries of the MS in the visitor list by the received registration request message of the MS(704); transmitting a registration response message to the MS through the MA3(705); transmitting the received registration request message to an HA(Home Agent) without change(706).