To share the fixed cost of a communication network, the private cost method allocates to each subscriber the cost of his dedicated terminal devices. The external cost method shares the connecting cost of user i between all of his correspondents in proportion of their traffic with i. All convex...

This paper analyzes single-till and dual-till regulations in terms of social welfare. We clarify two conditions to determine which regulation yields a higher welfare. The first condition is whether the solutions under welfare maximization yield positive or negative regulatory profits. The second...