AT&T said Monday that the Lumia 900, currently Nokia's top-of-the-line device on Microsoft's Windows Phone 7 platform, will be available to consumers in the U.S. starting April 8. The phone will be available on the AT&T 4G LTE network for $100 with a two-year contract.

The phone will also be available for preorder, in cyan or black, from AT&T's Web site starting on March 30. A white version goes on sale on April 22.

"The Lumia 900 is impeccably designed, with clean lines and a camera that rivals standalone digital cameras on the market today," said Jeff Bradley, senior VP for Devices, AT&T Mobility. "Combine that with the people-first Windows Phone experience and our 4G network--the nation's largest--and it's clear that this is one of the best phones customers can find."

[ Would availability of a single app affect your smartphone choice? See Angry Birds Shouldn't Seal Your Smartphone Choice. ]

For a $100 phone, the Lumia 900 does have some impressive specs. The camera boasts 8 megapixels, large aperture (F2.2), wide-angle focal length (28 mm), and optics from German lens specialist Carl Zeiss. The Lumia 900 also has a front-facing camera for videoconferencing. The phone is powered by a 1.4-GHz Snapdragon processor, and it sports a sizeable 4.3-inch ClearBlack AMOLED display.

Nokia said the 1830-mAh battery delivers 7 hours of talk time. Preinstalled apps include Facebook, Twitter, Linked In, and Xbox Live, which requires a subscription for online gaming.

The Lumia 900 is a key offering for both Microsoft and Nokia. Despite committing millions of marketing dollars to the Windows Phone platform, the companies have so far failed to make much of a dent in a market that is dominated by Apple and Google. Windows phones held just 4.4% of the U.S. mobile market as of January, according to market watcher Comscore. By comparison, Apple's iPhone held 29.5% of the market, while phones that run Google's Android OS held a collective share of 48.6%.

Microsoft has revealed that it's paying Nokia billions of dollars in research and development funds to transition virtually all of its mobile offerings to Windows Phone. To date, however, the investment shows few signs of paying off.

Still, Nokia remains the world's largest seller of handsets, by volume, and Microsoft hopes it can leverage the Finnish company's global distribution network to eventually make the Windows Phone platform a contender.

Microsoft also believes Google's $12.5 billion buyout of Motorola Mobility, announced last August, may push other handset makers, such as HTC and Samsung, more firmly into the Windows Phone camp.

The Enterprise Connect conference program covers the full range of platforms, services, and applications that comprise modern communications and collaboration systems. It happens March 26-29 in Orlando, Fla. Find out more.