A user purchases a card on which an identification number is printed and masked, calls a line for registration by the user's mobile telephone terminal in advance, inputs the identification number, and registers the telephone number of the mobile telephone terminal of the user in a settlement processing server. When the user buys a commodity at an affiliated store, the user calls a line for payment using the user's mobile telephone terminal the last N digits of the telephone number are treated as a payment amount of money, and inputs an access number of the affiliated store. When the settlement process is carried out by the settlement processing server, procedure completion information is sent from the telephone exchange to a terminal device having the access number at the affiliated store.