I n 1990, there were 11 million mobile phones in the entire world. Today, there are 50 million in Japan alone. Nearly 400 million people around the globe carry the various makes and models of wireless phones; those ranks swell by about 1 million more every week. Experts predict that within five years, that number will top 1 billion, surpassing the number of land lines. Mobile telephony is exploding because phones are getting smarter, becoming capable of doing just about everything a computer can. This is the dawn of the unwired world.

The boom is pushed by several factors. The first is the price of portable phones, which, like virtually all other electronic devices, has been plummeting. Even the top-of-the-line models now cost less than a third of what they did a few years ago.

But phones are only worth buying when they can be used, and the growth of a global infrastructure for wireless communications is the second key ingredient of the wireless boom. A truly worldwide web is just about in place. The pieces started to fall in place when Vodafone, a British cell-phone maker, bought AirTouch, an American rival, in January. That purchase forced other wannabe global contenders to respond in kind. Cable and Wireless bested NTT for International Digital Communications in Japan. MCI WorldCom bought Sprint last month; Germany's Mannesmann followed by purchasing Orange, Britain's third-largest operator. AT&T has teamed up with British Telecom to offer their customers service in 150 countries. And now Vodaphone AirTouch has launched a hostile takeover bid for Mannesmann.