To unnecessitate the throwing-in of coins and the usage of a card at the time of using a public telephone set.

A first exchange controlling the public telephone set 1 sends a subscriber's telephone number and password to a second exchange controlling subscriber's telephone sets 7 and 8 possessed by the user of the public telephone set and the second exchange collates them with the previously registered subscriber's telephone number and password of the user of the public telephone set. When the collating result is coincident, the first exchange connects the call to a subscriber's telephone number inputted by the user later to attain speaking, stores charging information for the speech and sends this charging information to the second exchange after the finish of the speaking. The second exchange receives the charging information from the first exchange to adjust the charge and then the first exchange blocks the line between the public telephone set 1 and itself.