Clearwire LLC (Nasdaq: CLWR) is kicking off the first phase of its Long Term Evolution Time Division Duplex (LTE TDD) network build out, announcing 31 cities where it will turn on the faster network by June 2013.

Markets to get the LTE TDD "hot zones" include congested urban cities New York City, San Francisco, Los Angeles, Chicago and Seattle; Clearwire said it would name the other 26 locations later. The LTE Advanced-ready network will include up to 8,000 sites.

Testing is underway, CEO Erik Prusch said on the company's first-quarter earnings call Thursday. Clearwire has not disclosed its vendors for the deployment.

Clearwire plans to spend between $350 to $400 million on the buildout, around $100 to $150 less than originally anticipated. Thanks to a sizable cash infusion from majority owner Sprint, it has $1.4 billion on-hand for the buildout. (See Clearwire Close to $200M in Vendor Financing .)

"We believe we'll be the first operators in the U.S. to push the limits of LTE technology, giving us the advantage of higher speeds and the best capacity in the nation," Prusch said.

The wholesaler continued to add new customers and partners ahead of launching its LTE network. Its first-quarter losses narrowed to $181.8 million from $226.9 million last year, and it added 586,000 subscribers for a total of 11 million -- up 80 percent from the previous year.

Sprint and Cricket Communications Inc. have signed on for Clearwire's forthcoming LTE network, and FreedomPop and Simplexity will resell WiMax. Clearwire also got a boost yesterday when Sprint announced it would offer prepaid services from its Boost Mobile and Virgin Mobile USA Inc. (NYSE: VM) brands over Clearwire's WiMax network. (See Sprint's Wild Week, Cricket Leans on Its Competitors for LTE, Cricket Taps Clearwire for LTE, FreedomPop Bets on 4G With Clearwire and Sprint's $2B Debt Play May Help Clearwire.)

Spectrum savior?
While all the wireless operators in the U.S. are bemoaning the spectrum shortfall, Clearwire's Prusch also tried to pitch the company as their one-stop savior. He said the supply of greenfield spectrum in the U.S. is insufficient, which is why Verizon Wireless 's cable deal has gotten a great deal of attention in the past few weeks. But, he doesn't believe Verizon's plan to acquire AWS spectrum from the cable consortium is practical or comprehensive enough. The better answer? Partner with Clearwire, of course. (See Verizon's Spectrum Auction: Winners & Losers .)

"We believe we're a better alternative than trying to piece together fragments of spectrum," he said, adding that Clearwire's 2.5GHz spectrum is ideal for data and for LTE TDD.

— Sarah Reedy, Senior Reporter, Light Reading Mobile