To provide a system for conducting the settlement of a relatively small amount of payment at low costs by using only a portable telephone in the same way as communication without making it necessary to use any complicate exclusive terminal or card or the like.

A communication network is constituted of a portable telephone group with an Internet connecting function beforehand joining in the prepaid contract of a communication fee, a switchboard connecting server computer for receiving the communication request information of the transmitter and receiver of the portable telephone through the Internet, and for transmitting this to the switchboard of an international telephone public network, and a charging server computer for holding the prepaid contract member information, and for withdrawing the communication fee. Then, a charging program for allowing the owner of the portable telephone to withdraw payment to the other owner from his or her own prepaid balance, and to add the sum to the balance of the other party by accessing a settlement mode on the Internet connecting function is added to the charging server computer, and a site for allowing the user to select the settlement mode or the communication mode is set.