The integration of telecommunications and data networks enables Internet Service Providers (ISPs) to develop increasingly services to attract customers. Designing rational pricing plans is very important for ISPs to reflect actual cost and to promote different services. In this paper, we discuss the applicability of the duration-based pricing scheme for charging Internet services that constantly occupy the resources. Then, we present a flexible time-based pricing policy considering service rate and time factors to design various pricing plans. Finally, the implementation issues and the advantages of adopting the time-based pricing policy in the billing system are discussed.