A communication parameter delivery server 50b has communication parameters necessary for making each of information terminals 13, 23 and 33 have a dial-up IP connection service. The server 50b delivers the communication parameters via each of networks 12, 22 and 33 responsively to a request from each of the information terminals 13, 23 and 33. The delivered communication terminals are set to Internet connection software installed in each of the information terminal 13, 23 and 33.