Since it was born in the late sixties, Internet has been changing the whole of human life. Because the demand on it is rapidly growing and its costs are increasing in geometric progression, it is argued that the service on Internet must be priced in proportion to the amount of usage. A recent research based on mathematical analysis found that perfect competition market results in the optimal degree of congestion of the information network. This research assumed the situation where network providers do their business independently; i.e. without interconnection of their networks. A lot of expectations were given on the future of the information networks like Internet, and this thesis reflects one of the main expections that all of the network in the world will be interconnected and form an integrated network. So, this thesis assumes the situation where network providers interconnect their networks together. We will see whether the degree of congestion of information network is optimal or not for two types of users(sensitive-to-Y user, insensitive-to-Y user) and three types of price scheme(connection price only, usage price only and both). Mathematical analysis enables us to know that regardless of the type of user, only usage price can give us the optimal degree of congestion.
