ABSTRACT
This chapter considers the market structure of Internet protocol (IP) telephony, while referring to supporting data and econometric analysis. In Japan the number of IP telephony customers exceeded 10 million in December 2005, and there are clear signs that widespread penetration of IP telephony is imminent. IP telephony is the routing of voice conversations over the Internet or other IP-based network using the voice over Internet protocol. IP telephony is provided as an additional service capability over broadband access services, mainly ADSL services. For example, this type of service enables subscribers to make and receive calls just as they would over the PSTN, among other subscribers to the same service provider at no extra cost. IP telephony not provided as voice service by telcos: computer (PC)-based IP telephony in which the call is made from a PC using the subscriber local loop and the public Internet for the transit trunk network.
