Nokia may sell more cellphones than any other company in the world, but it's been all but excluded from the United States for years -- and it's seen its global sales steadily shrink as the iPhone and Android smartphones have become the darlings of buyers in an increasing number of countries. Nokia's relevance has been fast receding, and its Symbian, Maemo, and MeeGo efforts became a pattern of failure for a company that just didn't get it. In response, a year ago, Nokia bet its future largely on Windows Phone 7, Microsoft's answer to Apple's iOS and Google's Android.

The first fruits of that partnership -- the Lumia 600 and 800 -- shipped last fall in Europe to disappointing sales. But the Nokia and Windows Phone faithful told skeptics to wait for the Lumia 900, which would prove that both Windows Phone and Nokia were poised to snatch victory from the jaws of defeat across the globe, particularly in the United States where it would be Nokia's turnaround product. Unfortunately, this Windows Phone flagship is no battleship. In fact, it can't even engage the competition in any serious way.

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That's too bad because aspects of both the Lumia 900 and Windows Phone show real promise and class. It's easy to be entranced by the "basic black dress" simplicity of the Lumia 900's design (available in blue, white, and black models), and the tiled interface of Windows Phone is truly inspired, elegant, and alluring. But if you look deeper, you find that the Lumia 900, like Windows Phone 7 itself, is a deficient product whose surface beauty masks a weakling.

The Lumia 900 costs $550 ($100 with a two-year contract) and runs on AT&T's network. It uses the standard Windows Phone 7.5 "Mango" operating system, adding nothing to address Windows Phone's many business shortcomings. Windows Phone 7.5 can't be used in most businesses because it lacks security features such as on-device encryption, VPN support, and support for Microsoft Exchange ActveSync (EAS) policies beyond the very basic set. Its Office suite is also primitive, with bare-bones capabilities far exceeded by apps available for other mobile OSes, such as the popular and capable Quickoffice for Android and iOS (but not for Windows Phone).

The iPhone's iOS of course offers the essential security and management capabilities, as well as business app selection, that make it a great fit in business. Android devices also have a decent selection of business apps. Though Android itself has weak security and management capabilities, Motorola Mobility's Android devices all add such iOS-level capabilities, as do some Samsung Android smartphones. A mom-and-pop shop might get away with using a Windows Phone device, but not most businesses. Windows Phone 7 -- and the Lumia 900 -- is more plausible for personal use.

Hardware

In many ways, the Nokia Lumia 900 is similar to the Samsung Focus S, perhaps the best-known Windows Phone smartphone in the United States. Both are as thin and light as an iPhone but a tad wider and taller (0.25 inch in each direction); they deliver a nice-size screen without taking up much more space in your pocket -- the same strategy of many Android smartphones. Their screens are 4.3 inches in diameter versus the iPhone's 3.5 inches. It's the size an iPhone should be, and the size of many Android smartphones.

At first blush, the Lumia 900's AMOLED screen is attractive: clear and bright, without the cartoonish colors of some Super AMOLED screens. But the more I used it, the more it bothered me. The screen resolution is a paltry 480 by 800 pixels, for a resolution of 217 pixels per inch (ppi). An iPhone's smaller screen has a resolution of 640 by 960 pixels, for a 326-ppi resolution. The Samsung Galaxy Nexus flagship Android smartphone has a 720-by-1,280 screen (316 ppi), and the no-nonsense Motorola Droid Razr Maxx has a 540-by-960 screen (256 ppi). In other words, the Lumia 900's screen is coarse by comparison and gives the impression of being lower quality.

The screen is just the start -- the Lumia 900's hardware is underpowered across the board. Like the Samsung Focus S, it uses a 1.4GHz single-core CPU, versus the faster dual-core CPUs of Android and iOS devices. Its 512MB of system RAM is half that of its Android and iOS competitors; its graphics coprocessor is also subpar. The 8-megapixel camera sounds impressive, but the results are disappointing compared to what the iPhone 4S and flagship Android devices' cameras deliver; the Lumia's pictures are a bit muddy and have a narrower tonal range. The battery power is also on the low side. Like the Focus S, the Lumia often can't make a full workday on a single charge, and its rated usage times are about half to two-thirds that of competing Android and iOS smartphones.

I'm surprised and disappointed that the Lumia 900 -- meant to be Nokia's best foot forward -- uses the same middling hardware as the Samsung Focus S, a device not trying to be the king of the hill. It's almost as if they are the same device in different bezels. The only real hardware difference is in the cellular radio: The Lumia 900 supports LTE 4G networks in addition to 3G GSM connections. As AT&T's LTE service is available in only a few dozen cities, that faster radio speed is one you may only rarely experience.

Few serious apps are available for Windows Phone, so the Lumia 900 feels snappy, but only because it's not doing much when in use. Microsoft is working on Windows Phone 8 (code-named Apollo) that allegedly will fix the many gaps in Windows Phone's capabilities, but I find it hard to trust that the underpowered hardware of the Lumia 900 will be able to run serious applications or games as Android and iOS flagship devices can today. I simply don't see the Lumia 900's hardware being able to keep up with Windows Phone and new apps if Microsoft were to get serious about the OS.

The Lumia 900's bezel is pleasant to hold. Although a slab, it's an elegantly simple one that draws character from its minimalism and subtle lines. There are the usual volume rocker, audio jack, MicroUSB jack, camera button, and front camera (1.3 megapixels), as well as the Wi-Fi, Bluetooth, and 3G-plus-LTE cellular radios. The simple design means the power and camera buttons are both unlabeled and identical in appearance, so it's easy to press the wrong one until your motor memory kicks in. There's no video-out capability, so forget about using the Lumia to make presentations via an HDTV or projector as you can with iPhones and many Android smartphones.

Beyond the hardware, the Nokia Lumia 900 offers no alterations to the Windows Phone 7.5 OS; you get the standard "Mango" experience.