A16 In October 2006, a new number portability system was introduced. Previously, changing one's mobile phone company required that one change one's telephone number and then inform

An advanced mobile-phone economy people of the new number. Thanks to the portability system, however, one can now change one's mobile phone provider without the need to change one's telephone number. The ease with which customers can change from one company to another has led to increased competition and, with a saturated market, the only way for mobile phone companies to increase their subscriber base is to poach subscribers from competitors, which has created a zero sum game.

Mobile phone charges in Japan are relatively high by international standards, but the entry of new market participants may trigger a price war.

With the spread of mobile and IP phones, fixed-line phones are no longer profitable and the mobile phone business has become an important revenue base and source of profits for telephone companies. Since it is, thus, vital that their mobile phone customers not be poached by competitors, competition to provide the best service is heating up.