Mobile phone firm Nokia has launched Lumia 800 smartphone in a move to regain its lost smartphone market, which is currently dominated by Apple's iPhone and other Android smartphones.

Lumia 800 is the fruit of Finnish company's partnership with Microsoft whose Windows Phone 7 operating system powers the latest smartphone.

The phone features a 3.7 inch AMOLED ClearBlack curved display blending seamlessly into the reduced body design and a 1.4 GHz processor. Nokia Lumia 800 contains an instant-share camera experience based on leading Carl Zeiss optics, HD video playback, 16GB of internal user memory and 25GB of free SkyDrive storage for storing images and music.

Lumia 800 is expected to compete with Apple's iPhone 4S, which was launched earlier this month amid much fanfare. The device has already become a hit with 4 million sales in the opening weekend.

iPhone 4S, which Apple claims as the most amazing iPhone yet, runs on iOS 5, packs a dual-core A5 chip, 8MP camera with advanced optics, full 1080p HD resolution video recording and Siri, an intelligent assistant that helps user get things done just by asking.

Let's see how Lumia 800 fares with iPhone 4S:

Display: Nokia features a 3.7 inch AMOLED ClearBlack curved display with a resolution of 800 x 480 pixels at 252 pixels per inch (ppi) density. iPhone 4S comes with 3.5-inch TFT Retina multi-touch display that may give a resolution of 960 x 640 pixels at 326 ppi density.

Design: Lumia 800 weighs 142 grams and has a dimension of 116.5 x 61.2 x 12.1 mm while iPhone 4S weighs 140 grams and has a dimension of 115.2 x 58.6 x 9.3 mm.

Operating System: Lumia 800 runs on Microsoft's Windows Phone 7.5 Mango OS. On the other hand, iPhone 4S runs on iOS 5, which has more than 200 new features including improved Notifications System, Newsstand and iMessage.

Processor: Lumia 800 packs a 1.4GHz Qualcomm chip with hardware acceleration and a graphics processor. iPhone 4S has a dual-core 1GHz A5 chip, ARM Cortex-A9 processor and PowerVR SGX543MP2 graphics chip.

Camera: Both phones have an 8MP camera with autofocus and dual LED flash. However, iPhone 4S scores over Lumia 800 in video capabilities as it can take videos at 1080 pixes at 30 frames per second (fps) while Lumia 800 takes videos at 720 pixels at the same 30 fps.

Storage: Lumia 800 comes with 16GB internal memory while iPhone 4S comes at 16/32/64 GB internal storage options. However, both phones lack external memory slot.

Battery: Lumia 800's 1450mAh battery gives up to 13 hours of talktime on 2G and 9.5 hours on 3G and standby time of 265 hours on 2G and 335 hours on 3G. The Apple smartphone has a Li-Po 1420 mAh battery, with 8 hours of talk time on 3G networks, up to 14 hours on 2G networks (GSM) and a standby time of 200 hours.

Pricing: The estimated retail price for Nokia Lumia 800 will be about $595, excluding taxes and subsidies. With a two-year contract, iPhone 4S costs $199 for the 16GB model, $299 for the 32GB model and $399 for the 64GB model. Unlocked iPhone 4S cost $649 for the 16GB model, $749 for 32GB and $849 for the 64GB.