Abstract
Today, telecommunication industry represents rapid expansion with various kinds of innovations in, especially, cellular phone. In this research, we try to clear up the development details from the viewpoint of industry activities. To do so, we put emphasis on the idea called "platform strategy" which derives from the characteristics of the cellular service as the principal axis. However, since the simple "platform strategy" has its limits to explain the diverse and rapid development of the mobile industry, we present the theory of "multi-tiered platform strategy" by classifying the innovations and considering cooperation between platform enterprises and contents or service providers.
