Relief is coming to iPhone users and others using AT&T's heavily used 3G wireless network in Seattle.

The company today announced a "substantial upgrade" of its network in the Puget Sound region from Everett to Tacoma, using additional wireless spectrum in the 850 MHz band.

"While specific benefits of the additional spectrum will vary by location, AT&T 3G customers should see improved quality and coverage throughout Seattle, Tacoma and surrounding markets," the release said.

The company said the upgrades are happening in Seattle, Tacoma, Everett, Renton and Auburn and Pierce and King Counties.

This comes as AT&T faces new competition in the region, where Clearwire is on track to roll out its faster, 4G network starting next month, and Verizon Wireless has been testing a new 4G service in Seattle with plans for service by next year.

The company's also in a spat over Verizon ads poking fun at AT&T's smaller 3G coverage in the U.S.

Meanwhile, AT&T's wireless traffic has quadrupled in the last year, driven by the iPhone and other smartphones used for Web access as well as calling.

The company's also providing 3G access to other devices such as the electronic books sold by Amazon.com and Sony.

Seattle-area upgrades have been made to its current 3G network using the 850 spectrum. They begin next year on a faster, HSPA 7.2 version that will be done in 2011.

The company's simultaneously adding nearly 1,900 cell sites nationally and new backhaul connections to support the mobile data traffic.

With one of AT&T's former lawyers now the incoming mayor of Seattle, the company may not expect much trouble getting permits for the new towers around here.