Sprint officials today announced an accelerated rollout of LTE wireless technology on Friday -- and said that it will continue to support its millions of Wimax smartphone and device customers beyond 2012.

Sprint officials told analysts that the company's LTE network will begin rolling out in some markets in mid-2012, and that it would reach some 275 million potential U.S. customers by early 2014.

During the Sprint network strategy update, which was also Webcast, CEO Dan Hesse said that Sprint will continue selling Wimax-based smartphones and devices running for the Clearwire network through 2012. Srint will support the Wimax devices for an unspecified period beyond 2012, he added.

Analysts estimate that about 17 million Sprint customers could be using Wimax networks by next year.

In a testy exchange amid questions about a potential Clearwire bankruptcy should Sprint halt its funding after 2012, Hesse repeatedly said he didn't know of any bankruptcy potential that would shut down Clearwire. He added -- at least twice -- that "No wireless bankruptcy has ever led to service being turned off."

Sprint would be a party to any possible Clearwire bankruptcy, he added. Sprint owns 54% of Clearwire.

One unidentified analyst told Hesse it would be "ridiculous" if Sprint didn't anticipate a Clearwire bankruptcy once Sprint stops funding it. The analyst's comment generated applause from her colleagues in the room.

Hesse didn't respond to the analyst's contention, though he did repeat that the Wimax service wouldn't be disrupted.

Earlier this year, Sprint said its LTE rollout would take three to five years to cover the country. At the time, officials said the build-out would start in some markets in mid-2012.

But Steve Elfman, president of network operations, said today that the rollout is "more likely a two to three year plan" that would be mostly complete by the end of 2013.

He called the project a "rapid LTE deployment--we're building as we're speaking."

The first LTE smartphones coming in mid-2012 will include Qualcomm technology running over the 1900 MHz wireless spectrum, Elfman said, without offering further details.

Fared Adib, vice president of product development at Sprint, said that Wimax is "an important part of Sprint's strategy" even as the carrier gradually moves to LTE.

Wimax, first launched as Sprint's first 4G network in October 2008, gave Sprint a "first to market" advantage, Sprint officials said.

Since then, Verizon Wireless and AT&T have started rolling out LTE service in U.S. cities.

Verizon has said its LTE network offers downloads of data at 5 Mbps to 12 Mbps, while AT&T has not disclosed download speeds for its LTE network.

Sprint, whose Wimax network operates at up to 9 Mbps for downloads, hasn't stated what its LTE speeds are expected to be. Sprint officials did tell analysts Friday that the LTE network will be somewhat faster than its Wimax offering.

Investors have been concerned about the expected cost of Sprint's move to LTE, especially after it rolled out Wimax on the Clearwire infrastructure. Sprint CFO Joe Euteneuer argued that the Wimax move gave Sprint an early 4G lead, making the investment worthwhile.

Sprint has a two-year, $1 billion agreement to use Clearwire's Wimax network service through 2012, Hesse said, adding that Clearwire is also moving to a different version of LTE from Sprint as well.

Sprint expects to save $11 billion in the next six years with its so-called Network Vision project, first announced last year.

Sprint put the cost of the project at $4 billion to $5 billion at the time of the announcement, although analysts said Friday that it could be as high as $10 billion when LTE upgrades and other factors are fully accounted for.

The Network Vision project will consolidate Sprint's existing 3G CDMA network switches and cell tower antenna infrastructure with the coming 4G LTE network.

It also phases out the iDen network in 2013 that has been used to support Push-to-Talk (PTT) devices mostly used by service workers. Sprint launched PTT over its CDMA network on Oct. 2 while introducing a new ruggedized PTT phone.

The retired iDen network will free up 800 MHz spectrum that Sprint said it will "harvest" it for other purposes still being considered.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed . His e-mail address is mhamblen@computerworld.com.