A fair and secure mobile billing system

Abstract

All mobile phone subscribers must pay a subscription fee to enjoy the convenience of this technology. Subscribers pay for the actual time spent talking on the cellular phone. Generally, there are two kinds of billing. With prepaid service, the subscriber buys a prepaid card and pays for the cellular phone service in advance. As the subscriber uses airtime the cellular phone account is debited the appropriate amount of cellular phone service used. When the subscriber runs out of dollars in the cellular phone account, they can no longer call until the account is prepaid for additional cellular phone service or airtime. With postpaid service, cellular carriers bill customers based on how many minutes of airtime they use each month. When the customer places a call on an activated cellular phone, each minute the phone is connected is counted. Cellular carriers bill the customer on a monthly basis for the airtime used. There are some issues worth discussing such as fairness, non-repudiation, and non-usurpation. In this paper we propose a fair and secure mobile billing system. We introduce the "observer" concept to supervise billing to make it more objective and accepted by both cellular carriers and subscribers. The proposed scheme can detect illegal phone calls in real time and the subscriber cannot deny the deserved fees. (c) 2004 Elsevier B.V. All rights reserved.