Patent ID: 7499440

Claim:
A communication system connecting a LAN and a radio communication terminal through a radio packet communication network by a network connection service dynamically giving an IP address within a first address space at the time the network is connected; wherein a network router is provided at a boundary point between the radio packet communication network and the LAN; wherein the radio communication terminal comprises a communication device connecting to the radio packet communication network, high-level equipment performing a communication by using the communication device, and a connection adapter interposed between the communication device and the high-level equipment and performing a relay of the communication; wherein the high-level equipment is allotted in advance with an IP address for a network connection service fixedly giving an IP address within a second address space as its own IP address, and moreover, an IP address within a third address space is fixedly set as an IP address of a terminal of a LAN side; and wherein the connection adapter comprises a communication control unit which mutually converts the IP address within the first address space stored in a header of an IP packet to be transmitted and received and the IP address within the second or third address space therebetween.