Access to the Internet is provided by a number of commercial entities known as Internet Service Providers who constitute the Internet backbone and act as mediators between the user and the Internet. A variety of pricing methods have been considered in the literature and implemented in practice. While congestion control is a necessary condition for the smooth operation of the global Internet and affects all users, demand for service differentiation is related to the requirements of specific applications using the Internet as an infrastructure. The pricing model of an Internet Service Provider needs to be able to accommodate the levels of service offered.