The great wireless revolution, which took off with the spectacular spread of cell phones in the 1990s, and which is supposed to bring broadband Internet to the gadget in your pocket, is in trouble.

Demand is soaring, forcing makers of wireless equipment and network operators to invest billions to meet humanity's inexhaustible thirst for getting connected anywhere, anytime. Global sales of mobile phones soared from seven million in 1990 to 700 million last year and are projected to reach 1.7 billion in 2005. More and more users expect their phones to deliver very clear voice signals and to pick up their e-mail, albeit slowly.

But as frustrated callers know, communicating with mobile phones is tricky. The problem: today's wireless networks use a maze of incompatible transmission standards, so road warriors aren't guaranteed a dial tone when they travel. U.S. wireless operators alone use three competing standards, and just one of these is compatible with the leading standard in Europe, which itself has several variants. Most Asian wireless networks are built to another standard. This radio-wave Babel prevents most mobile phones in the United States from being viable elsewhere. It also limits U.S. manufacturers' economies of scale against foreign competitors.

The wireless revolution's troubles go beyond conflicting standards. Consumers consistently expect more advanced features, so models that were state of the art in, say, 1995 will seem antique by 2003. By then, almost all new mobile phones will offer some form of Internet access. Millions of people in Japan, for example, snapped up i-mode, a service that lets them use cell phones to send text messages, buy stocks and check sports scores. Worldwide, companies are spending billions to build a new network, usually referred to as "third generation," or 3G, that is expected to bring broadband-detailed Web pages, music, even video-to your mobile phone.

However exciting for consumers, these advances carry a price, since there's currently no easy way to upgrade mobile phones, or the base stations that carry their signals to the network, without changing hardware. Moreover, the wireless industry can't predict which offerings will be winners; the consequences of failing to guess right can be devastating. Last year, European wireless operators spent heavily to offer phones equipped with a format known as Wireless Access Protocol, only to find the buying public impatient with their slow download speed. Demand was limp.