Critical mass of users versus critical mass of services in a multiproduct information service system

In this paper we study the economic behaviour of the suppliers of a set of advanced telecommunications services with a joint adoption cost (common access facilities, learning process, etc.). In fixing the two-part tariffs for their services the suppliers have to share the burden of leaving to the users a surplus sufficient to cover the adoption cost. The lack of coordination in supplying a critical mass of services or in the pricing decisions has high changes to result in suboptimal or unviable diffusion of the new technology as a whole. We present a static optimization model of user behaviour, and derive access and usage demand with a two-part tariff and a joint adoption cost. We compare noncooperative and cooperative market equilibria in a duopoly with perfect information; finally we discuss the extension of our analysis to the case of imperfect information in a dynamic setting.