Microsoft used the Consumer Electronics Show in Las Vegas to show off two upcoming additions to its Windows Phone lineup that will be the first to run on AT&T's high-speed LTE network.

The HTC Titan II features a high-end camera with 16 megapixels, the most on AT&T, and a 4.7-inch display, the largest of any Windows phone. The Nokia Lumia 900 boasts a 4.3-inch AMOLED ClearBlack display and a front-facing camera for video chat.

During his CES keynote presentation on Monday, Microsoft chief executive Steve Ballmer said the "blazing fast" Lumia 900 would be "heavily promoted" in all of AT&T's 2,400 U.S. stores. Microsoft did not provide ship dates or pricing details for the Lumia 900 or Titan II. The Lumia 710, Nokia's first Windows Phone for the U.S. market, hits stores on Wednesday.

[ Are there holes in Microsoft's mobile lineup> Read 2012 Tablet Race: Where's Microsoft? ]

Nokia, which is porting virtually all of its devices to Windows Phone under a formal partnership with Microsoft, has also reached an exclusive deal with Electronic Arts to bring a number of mobile games, including FIFA 12, Madden 12, and NBA Jam, to its Windows phones.

Microsoft launched its Windows Phone 7 platform in late 2010 amid considerable hype. But so far consumers have mostly rejected devices based on the OS. Windows Phone's distinctive interface, which is built around blocks of screen real estate called Live Tiles, is a departure from the standard, icon-based approach used by Apple's iPhone and Google Android.

The design has won praise from numerous reviewers, but Windows Phone's 1.5% market share indicates consumers aren't ready to embrace it. Ballmer said he's convinced that will change.

"I'm really excited and upbeat about where we are, we definitely took a different approach than everybody else and I think we've got a unique and beneficial experience," said Ballmer, alongside keynote host Ryan Seacrest. "The thing I'm really pumped up about actually is the work that's going on in moving to 4G LTE networks," Ballmer said.

Ballmer is putting Microsoft's money where his mouth is. At CES, the company on Tuesday and Wednesday is offering $100 to attendees who visit the Microsoft booth and can show that their current smartphone is faster than a Windows Phone.

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