This paper introduces the Electronic Commerce Payment System-Telephone Number(ECPS-TN) with a deferred payment method that bills the price of merchandise in electronic commerce shopping mall based on business to customer(B2C) together with a telephone bill, and presents its configurations, functions, and performances. The ECPS-TN consists of a server and gateway system that presents the service of ECPS-TN which can be linked by the present electronic commerce shopping mall of the Web/Merchant server, customer management and billing system, and the TCP/IP. By introducing a different payment method from the present payment such as credit card, electronic money wallet, and on-line depositing, it can not only serve a variation of payment but also secure a member of service for almost of users by using the system that bills the price of merchandise in electronic commerce shopping mall together with the number of Public Switched Telephone Network/Integrated Service Digital Network (PSTN/ISDN) which belongs an average Internet user.