Patent ID: 7242689

Claim:
A mobile internet-protocol (IP) communication terminal that supports a first IP, and can be connected to a first network that supports the first IP and a second network that supports a second IP that is different from the first IP, wherein when the mobile IP communication terminal is connected to the second network via a second repeater and performs a packet communication with an IP communication terminal that supports the first IP, the first network and the second network are connected via a translator to perform a packet communication, and the mobile IP communication terminal registers a connection position of the mobile IP communication terminal with a first repeater that has a packet transfer function, the mobile IP communication terminal comprising: an IP deciding unit that decides whether the mobile IP communication terminal is connected to the first network or the second network; a unique-address generating unit that generates a first address that is unique to the mobile IP communication terminal, when the IP deciding unit decides the mobile IP communication terminal is connected to the second network; a translator-through address generating unit that generates a second address so as to connect the mobile IP communication terminal to the first network via the translator, based on position information of the translator stored in the second repeater, and a translator-through position-registration-signal transmitting unit that transmits a registration signal, for registering the connection position, to the first repeater, the registration signal including a destination address and a source address, the destination address having the second address and an address of the first repeater, the source address having an address of the connection position, and the address of the connection position corresponding to the second IP and acquired from the second network.