Ramsey pricing in one-way and two-way interconnection between telephone networks

I derive Ramsey optimal prices in one-way access of long-distance operators and enhanced service providers to local loops. As long-distance services and enhanced services become substitutes due to the advance of Internet telephony, the Ramsey principle requires higher access charges assessed on both services. I also derive Ramsey prices in two-way interconnection between fixed-link and mobile phone networks, which turn out to be formally equivalent to those for the one-way access above. This result suggests that the price of fixed-to-mobile calls should be higher than the price of mobile-to-fixed calls when the substitutability of calls to double subscribers is more prominent than the substitutability of calls of double subscribers, and vice versa.