The digital switch is the end of one TV era, but broadcasters and device companies hope it's opening up another.
Their vision for the future: a world in which we access live television not just on big screens in our living rooms, but also on cellphones and computers and in cars.
On Thursday, when stations will be required to broadcast through digital rather than analog signals, some companies will use the broadcast spectrum freed by the switch to transmit live television to cellphones and other portable devices. Shows and live video clips are already available on some phones, but this heats up competition as broadcasters and cellphone companies vie to turn the feature into a must-have.
"This is one of about six or seven or eight things people are going to use their phone for," said Rob Hyatt, executive director of premium content at AT&T; Inc.
About 13 million people watched video on their cellphones in the first three months of this year, which is about 6% of all mobile subscribers, according to Nielsen Co. That's a 50% increase over the same time last year.
The feature might not take off -- Virgin Mobile yanked its cellphone TV offerings in Britain in 2007, saying not enough subscribers had expressed interest. But most carriers today are betting that it will. What's still to be determined is which service will prevail.
San Diego-based Qualcomm Inc. hopes consumers will use Flo TV, which it's been building since 2003. On Friday, the availability of more bandwidth will enable Flo TV to double the number of mobile customers it can reach.
Broadcasters will be pushing customers to use service provided by the Open Mobile Video Coalition, a group that represents more than 28 station groups in the U.S. and will broadcast local TV to mobile handsets, netbooks and MP3 players.
Some early adopters are already using MobiTV, a service from the eponymous Emeryville, Calif., company that provides on-demand video and live TV over a carrier's data network rather than over a television spectrum.
For Qualcomm, the stakes are high. It invested at least $800 million in building the Flo TV network, hoping to drive demand for the chips it makes.
Qualcomm began working on the network after paying $38 million in a federal auction in 2003 for Channel 55, a UHF frequency that becomes available for use Friday.
"What we see is that people are on the go and have the need for immediate gratification," said Bill Stone, president of Flo TV Inc., which is a wholly owned subsidiary of Qualcomm.
But it hasn't all gone as planned. The company lost tens of millions of dollars when Congress voted in February to delay the digital TV switch. Flo TV is available on only nine cellphone models and only to Verizon and AT&T; subscribers, because it requires a special chip that is not installed on most phones.
And because of the size of the spectrum Qualcomm purchased, Flo TV offers 12 channels. MobiTV offers more than 40 in certain areas.
"We project the growth is not going to be incredibly dramatic" for Flo TV, said Lewis Ward, research manager at research firm IDC. "There's been a big learning process for them here."
The young consumers who are more likely to watch television on their mobile phones tend to watch on-demand programs -- videos that can be played whenever the viewer chooses -- rather than live TV, Ward said. And the Open Mobile Video Coalition will be a hefty competitor, offering free local TV, he said.
As a result, Ward said, Qualcomm is "looking at Plan B."
That includes offering Flo TV in cars with entertainment systems and eventually transmitting it to portable screens that operate independent of carriers. Those systems would require a small device containing a chip to be installed on a DVD player or phone.
Stone acknowledges that Flo TV might have been launched too early, before it was available on enough devices or had enough coverage, but he says there's a plus to that.
"We are now the network for live broadcast mobile TV in the U.S.," he said. "If someone wants to build a competing network, it's going to take a lot of time."
But competitors don't need to build a competing network to give Flo TV a run for its money. The Open Mobile Video Coalition needs to pay only $50,000 to $150,000 per station to install mobile transmitters and send out TV channels to cellphones, said Anne Schelle, executive director of the coalition.
Broadcasters have an advantage because they don't need to buy spectrum and don't have to find new programming or content. Manufacturers such as LG have been happy to make devices that can receive this signal and will roll them out by the end of the year, she said.
"You can turn any video-enabled device into a TV set," Schelle said.
MobiTV operates over a cellular network and is available on most devices without any special chip. It's often choppier than Flo TV, but data transmission will become faster as networks switch to 3G and eventually 4G, said Paul Scanlan, co-founder and president.
MobiTV just reached 7 million subscribers. It has the advantage of being included in such programs as Sprint's Simply Everything plan, getting subscribers who sign up for unlimited data, text and voice service.
Consumers can also get mobile TV with help from Transpera Inc., which provides the platform for networks such as CBS and MTV to deliver video to cellphones. The videos contain ads so viewers don't have to pay to watch them.
Although the videos aren't live, Transpera posts new ones on the Web soon after news breaks, company founder Frank Barbieri said.
Transpera's network has recently seen a 200% increase in viewership quarter over quarter, he said.
Barbieri said he thought Flo TV "is "going to go down as one of the colossal business mistakes of the first decade" of the 21st century.
Still, analysts agree that we'll be watching a lot more TV on our cellphones pretty soon, one way or another. Terry Denson, vice president of content strategy and acquisition for Verizon Wireless, said his company anticipated that it would become mainstream in the next three years.
If that seems strange, just remember that it combines two things Americans love: cellphones and television.
"TV is still the great American pastime," Scanlan said.