Abstract: Apparatus and method for seamless handoff of a service between different types of networks. The system may include a first user equipment, a second user equipment, a first network, a second network, and an application server. The first user equipment and the second user equipment may be configured to communicate with each other initially through a first data path of the service. The first network may be configured to determine whether the first user equipment should change its access network from the first network. The second network may be configured to allocate a new bearer and a second network IP address to the first user equipment when the first network requests the first user equipment to change its access network from the first network to the second network.

Abstract: Provided are a method and system for preventing the use of a stolen terminal when the stolen terminal registers its location again by making it inevitable for the stolen terminal to register its location again to be used. The method includes: receiving information that a user terminal was stolen; making a mobile application part (MAP) cancel location request to a mobile switching center (MSC) or a serving general packet radio service support node (SGSN) after receiving the information that the user terminal was stolen; and checking whether the user terminal is a stolen terminal when receiving a location registration approval request from the user terminal after performing a MAP cancel location process by deleting subscriber information of the user terminal from the MSC or the SGSN in response to the MAP cancel location request.

Abstract: Apparatus and method for seamless handoff of a service between different types of networks. The system may include a first user equipment, a second user equipment, a first network, a second network, and an application server. The first user equipment and the second user equipment may be configured to communicate with each other initially through a first data path of the service. The first network may be configured to determine whether the first user equipment should change its access network from the first network. The second network may be configured to allocate a new bearer and a second network IP address to the first user equipment when the first network requests the first user equipment to change its access network from the first network to the second network.

Abstract: Provided are a method and system for preventing the use of a stolen terminal when the stolen terminal registers its location again by making it inevitable for the stolen terminal to register its location again to be used. The method includes: receiving information that a user terminal was stolen; making a mobile application part (MAP) cancel location request to a mobile switching center (MSC) or a serving general packet radio service support node (SGSN) after receiving the information that the user terminal was stolen; and checking whether the user terminal is a stolen terminal when receiving a location registration approval request from the user terminal after performing a MAP cancel location process by deleting subscriber information of the user terminal from the MSC or the SGSN in response to the MAP cancel location request.

Abstract: A method for a mobile node's connection to a virtual private network using a mobile IP under a mobile environment is provided. According to this method, the mobile node firstly makes a mobile IP registration request message including VPN user authentication information and transmits the message to VPN gateway. Then, the VPN gateway reads the VPN user authentication information from the message and inquires a database in which VPN user authentication information is already stored, to verify a VPN access authority of the mobile node. If the access authority is verified, private IP is recorded in a response message to the mobile IP registration request message, and the response message is transmitted to the mobile node to assign the private IP. Accordingly, a VPN having low construction cost, simple topology, less network traffic and low working loads on the mobile node and the network under a mobile environment can be constructed.