The companies will bring competition to a Baltimore wireless market whose sole fourth-generation wireless broadband offering right now is from Clearwire, a Seattle-based company that uses a different technology standard, known as WiMax.

Clearwire, which sells its service in Baltimore under the Clear brand name, starts at $50 a month for home and mobile service. At least one phone from its partner, Sprint, can access the 4G network for Internet data service. Clearwire has rolled out its 4G offering to dozens of U.S. cities, though it is also considering switching to LTE technology.

It could be several years before consumers can take full advantage of 4G networks, as cell phone manufacturers will have to develop mobile devices with new internal communications hardware, according to industry analysts. The adoption of 3G in the U.S. has been slower than anticipated, with less than 30 percent of consumers using the technology, according to a July study by NERA’s Dippon.

For the next few years at least, big companies like AT&T and Verizon will likely offer consumers a mix of 3G and 4G services. Consumer pricing for 4G services is not yet available from the carriers.

“4G will be a complement service, not a substitute,” Dippon said. He said the approach most carriers will take will be to offer Internet data services over 4G, while keeping voice communications on 3G networks.

Verizon is furthest along in the race. It plans to roll out 4G service in 38 markets by the end of this year, covering about 110 million people, plus 60 airports – including BWI Thurgood Marshall Airport. The buildout involves installing new hardware on the company’s cell towers.

Initially, Verizon’s 4G network will offer data services to consumers – such as 4G mobile broadband modems for use in laptops -- and voice calling will eventually follow in mobile devices that can tap both the 3G and 4G networks. The company expects download speeds to be in the range of five to 12 megabits per second – several times faster than 3G download speeds.

“This 4G network is a complete overhaul for us,” said Jim Haskins, a Verizon Wireless vice president and regional director of business data sales for the Baltimore area.

AT&T Wireless is testing LTE in Baltimore and Dallas this year and plans to cover more than 70 million people by the end of next year. Download speeds for the 3G network, after a planned upgrade this year, will top 7 megabits per second – and its 4G LTE service will be even faster, according to AT&T.

In the meantime, AT&T continues to pour millions billions of dollars into upgrading its 3G network, because it will continue to see high use from subscribers. The company has been the exclusive carrier of Apple’s iPhone, whose users consume a lot of bandwidth on the 3G network.

“It’s going to take 4G several years to really scale,” said Mark Siegel, an AT&T Wireless spokesman. “We will continue investing in our 3G network. We’re doing both at the same time.”

Both Verizon and AT&T may see competition from a new player on the block: Reston, Va.-based LightSquared Inc. LightSquared plans on rolling out a new 4G network that uses both satellite and LTE wireless cell tower technology to deliver phone and data services to consumers’ mobile devices.

But the company won’t be selling directly to consumers – or competing directly with telecom carriers for customers. Instead, it is pursuing a wholesale model where it strikes deals with third parties who want to sell their own wireless broadband plans to their consumers.

If LightSquared’s plans come to fruition, consumers could see pitches to buy wireless plans from big-box retailers, large websites, or even computer and mobile device manufacturers. The model could threaten traditional wireless operators, such as Verizon, AT&T and Sprint.

LightSquared thinks it has an advantage because the phones that use its service will be able to communicate via satellite, and not just a land-based cellular tower system. That means consumers who are on the LightSquared network will theoretically always have a signal.

“What the satellite capability gives you is 100 percent coverage in the United States,” said Tom Surface, a LightSquared spokesman.