Patent ID: 7328281

Claim:
An address translator to connect a first network conforming to a first protocol, a second network conforming to a second protocol, and a mobile terminal in the first network, the mobile terminal having a visited network address used in a visited network and a home network address used in a home network, the address translator comprising: a storage unit for storing information of a correspondence between a visited network address of the mobile terminal conforming to the first protocol and a home network address of the mobile terminal conforming to the first protocol, and translation information between the home network address of the mobile terminal conforming to the first protocol and a home network address of the mobile terminal conforming to the second protocol, wherein the home network address of the mobile terminal conforming to the first protocol is assigned to the home network address of the mobile terminal conforming to the second protocol and a correspondence between the assigned home network address of the mobile terminal conforming to the first protocol and the home network address of the mobile terminal conforming to the second protocol is registered as the translation information when the home network address of the mobile terminal included in a response to a request for connecting to the mobile terminal from another terminal passing through the address translator is an address conforming to the first protocol; a processing unit for translating an address in a packet received from another terminal in the second network from the second protocol to the first protocol based on the translation information and determining the visited network address of the mobile terminal that uses the translated address as the home network address conforming to the first protocol; and a transmission unit for transmitting the received packet with the visited network address as a destination address to the mobile terminal.