To enable payment of telephone call charge in a store handling a portable telephone set and a telephone card, when they are used.

This system consists of a portable telephone set 1, with which the identification number and the user ID of a connected telephone company are preliminarily registered, a telephone card 1', a store processing terminal device 30 and POS terminal 40 of a store handing this, and the managing host computer 100 of a telephone company. In the system, they are connected by a communication line, the merchandise information of a transacted portable telephone set is transmitted to and stored by the host computer, and when communication by using the portable telephone is performed, the host computer performs subtraction processing of a prepaid telephone call charge according to the amount of communication from the stored merchandise information of the portable telephone set.