WASHINGTON — Wireless devices such as Apple's iPhone are transforming the way we go online, making it possible to look up driving directions, find the nearest coffee shop and update Facebook on the go. All this has a price — in airwaves.

As mobile phones become more sophisticated, they transmit and receive more data over the airwaves. But the spectrum of wireless frequencies is finite — and devices like the iPhone are allowed to use only so much of it. TV and radio broadcasts, Wi-Fi networks and other communications services also use the airwaves. Each transmits on certain frequencies to avoid interference with others.

Now wireless phone companies fear they're in danger of running out of room, leaving congested networks that frustrate users and slow innovation. So the wireless companies want the government to give them bigger slices of airwaves — even if other users have to give up rights to theirs.

"Spectrum is the equivalent of our highways," says Christopher Guttman-McCabe, vice president of regulatory affairs for CTIA-The Wireless Association, an industry trade group. "That's how we move our traffic. And the volume of that traffic is increasing so dramatically that we need more lanes. We need more highways."

That won't happen without a fight. Wireless companies are eyeing some frequencies used by TV broadcasters, satellite-communications companies and federal agencies such as the Pentagon. Already, some of those groups are pushing back.

That means tough choices are ahead. But one way or another, Washington will keep up with the exploding growth of the wireless market, insists Rep. Rick Boucher, D-Va. He is sponsoring a bill that would mandate a government inventory of the airwaves to identify unused or underused bands that could be reallocated.

CTIA, the industry group, is asking the government to make an additional 800 megahertz of the airwaves available for wireless companies to license over the next six years.

That would be a huge expansion from the industry's current slice of roughly 500 megahertz. The Federal Communications Commission is preparing to make more frequencies available for commercial use, but has just 50 megahertz in the pipeline.

Two trends are driving the demand.

First, advanced new wireless applications — such as mobile video and online games — devour far more bandwidth than voice calls or basic text messages, says Neville Ray, senior vice president for engineering operations for T-Mobile USA Inc.

Second, consumers are flocking to wireless Internet connections, in some cases dropping landline accounts altogether. ABI Research projects U.S. mobile broadband subscriptions will climb to 150 million by 2014, up from 48 million this year and 5 million in 2007.

The predicament, says Jamie Hedlund, vice president of regulatory affairs for the Consumer Electronics Association, is that many users "assume the wireless experience should be the same as the wired experience, but the capacity is just not there for that."

The industry's concerns are finding a sympathetic ear in Washington.

Julius Genachowski, chairman of the FCC, says finding more room for the wireless industry will be an important part of his agency's broadband plan. That plan, mandated by the 2009 stimulus bill, is due in February and will propose using wireless systems to bring high-speed Internet connections to corners of the country that are too remote for landline networks.

"If we are going to have a world-leading broadband infrastructure for the nation, wireless is an indispensable ingredient," says Genachowski aide Colin Crowell.

Lawrence Strickling, head of the National Telecommunications and Information Administration, the arm of the Commerce Department that manages the federal government's use of the airwaves, says the agency is also hunting for more frequencies the wireless industry can use.

Some of the crunch can be addressed with technologies that make more efficient use of airwaves and new equipment that lets users share bands. The FCC also wants to promote greater use of frequencies that aren't licensed to anyone, such as the "white spaces" between the bands used by TV channels.

But such solutions alone won't solve the crisis, the wireless industry warns.

The FCC's attention for now is on TV broadcasters, which hold nearly 300 megahertz of airwaves that are mainly used to serve just 10 percent of American homes — those that still rely solely on over-the-air TV signals.

The FCC is exploring multiple options, most of which would leave broadcasters with enough capacity to deliver a high-definition signal over the air.

One possibility, which might require congressional approval, is a voluntary program that would let broadcasters sell excess bandwidth through an auction, to either the government or directly to wireless companies. Although the FCC awarded spectrum licenses to broadcasters for free many years ago, those licenses are worth millions today.