Apple Inc.'s next-generation iPhone 4S is fast becoming the people's favorite smartphone. Apple, AT&T and Verizon have exhausted their pre-order supplies of the iPhone 4S, which will begin delivery on Oct. 14, according to media reports.

According to AT&T, more than 200,000 iPhone 4S handsets have already been pre-ordered in the first 12 hours of availability, raising the prospect of the device shattering all previous sales records for Apple products.

Apple replaced the Oct. 14 delivery date for pre-ordered iPhone 4S phones with a Ships: 1-2 weeks notice on their Web site, by late Friday. AT&T's Web site disclosed that the iPhone 4S would ship in 21 to 28 days, while Verizon fixed a delivery date of Oct. 21.

Sprint Nextel stated that the lowest priced model (the 16GB variant) was out of stock but the more expensive 32GB and 64GB versions were still available for delivery, either on Oct. 14 or 15.

Back in 2010, Apple said it sold 1.7 million units of the iPhone 4 from the start of pre-orders - June 15 through June 26 - three days after the new model reached retail stores.

Apple unveiled the iPhone 4S, instead of the eagerly-anticipated iPhone 5, on Oct. 4. As it turned out, the smartphone from Apple featured some important upgrades that were rumored to be a part of the imaginary iPhone 5, like the 1GHz dual-core ARM Cortex-A9 processor, PowerVR SGX543MP2 GPU, an Apple A5 chipset and an 8 megapixel camera. It also has a 3.5-inch TFT Retina multi-touch display and is loaded with the latest Apple operating system iOS 5.

Sporting a high-speed download packet access (HSDPA) technology, the iPhone 4S will have data download speed that is nearly twice as fast as the iPhone 4. However, missing were prominent specs like edge-to-edge design, a larger display, 4G LTE and Near Field Communication (NFC) technology.

The iPhone 4S, which measures 115.2 x 58.6 x 9.3 mm, weighs 140 grams. The iPhone 4 weighs 137 grams. It has a rear-facing 8 megapixel LED flash camera with 1080p HD video recording capabilities and a front-facing VGA camera for video chats.

It also comes with alternating antennae for better call reception, CDMA and GSM support, a personal assistant called Siri, iCloud and Bluetooth 4.0 wireless technology.

The Apple smartphone has a Li-Po 1,420 mAh battery, with 8 hours of talk time on 3G networks and up to 14 hours on 2G networks (GSM). With a two-year contract, the iPhone 4S costs $199 for the 16GB model, $299 for the 32GB model and $399 for the 64GB model. Apple-listed prices for a contract-free phone in the United States are $649 for the 16GB model, $749 for 32GB and $849 for the 64GB.

The Apple iPhone 4S, despite sporting several new upgrades, is sure to come under fire from Android-based smartphones. Does it have enough firepower to challenge the top 5 'super' smartphones that run on Google Inc.'s Android OS?

The top iPhone 4S challengers are the Samsung Galaxy S2, the Motorola Droid Bionic, the Motorola Photon 4G, the HTC Sensation 4G and the HTC EVO 3D.

Samsung Galaxy S2

The Samsung Galaxy S2 has officially sold 10 million units since its global launch in late April. The Galaxy S2 debuted at the Mobile World Congress in Barcelona in February and the phone was later launched in Europe and South Korea. It also went on sale in China in July, before hitting the U.S. markets in September.

The device, which runs on the Android 2.3 Gingerbread OS and sports Samsung's TouchWiz UI, comes with an 8 megapixel camera with flash and can record HD video in 1080p, offering the richest video content on a smartphone. The phone also has a front-facing 2 megapixel camera for video chat. The phone comes with 16/32GB internal memory configurations with 1GB RAM.

The Galaxy S2 comes in three variants, on AT&T, T-Mobile and Sprint (the latter's version is called Samsung Galaxy S2 Epic 4G Touch). All versions of the Galaxy S2 will get 4G treatment, offering data speed up to four times faster than Apple's iPhone 4.

The Samsung Epic 4G Touch on Sprint measures 129.5 x 68.6 x 9.6 mm and weighs 129 grams. The T-Mobile version, fondly known as Hercules, measures 131 x 70 x 9 mm. The AT&T version retains the original 4.3-inch display and therefore measures 125.3 x 66.1 x 8.5 mm and weighs 116 grams. The other two have a 4.52-inch display screen.

The Sprint and AT&T variant of the Galaxy S2 is powered by a dual-core 1.2 GHz ARM Cortex-A9 Mali-400MP GPU Orion chipset, while the T-Mobile variant will be powered by a 1.5 GHz dual-core Qualcomm APQ8060 processor.

The Samsung Epic Touch 4G has Li-ion 1800 mAh battery support, which will offer more than 10 hours of talk time, while the AT&T version retains the Li-Ion 1650 mAh battery found in the original Galaxy S2.

Additionally, Samsung announced a LTE version of the Galaxy S2 smartphone, which features a 4.5-inch Super AMOLED screen with 800x480 screen resolution. It is powered by a 1.5GHz dual-core processor and offers 16GB internal memory. The phone is 0.37-inches thick and weighs 4.6oz. The Galaxy S2 LTE will also feature a 8 megapixel rear-facing camera and a 2 megapixel front-facing camera. It is fitted with a Li-on 1850 mAh battery. The phone will come pre-loaded with Android Gingerbread.

A Betanews poll survey showed that 75 percent of the 2,763 participants had plans to purchase a Galaxy S2 within three months, while almost nine percent have decided to buy an iPhone, according to the Christian Post.

Motorola Droid Bionic

The Droid Bionic was hyped for months when it was originally announced at the Consumer Electronics Show in Las Vegas, Nev. in January. The 4G LTE, dual-chip phone had been delayed for quite some time as Motorola made numerous changes, allowing it to compete with the high-end phones of the industry.

The delay seems to have borne fruit. The phone comes with a 4.3-inch HD screen featuring the Corning Gorilla scratch-free screen, a 8 megapixel rear-facing flash camera with 1080p HD video capture, a front-facing VGA camera for video chat over 4G LTE, 3G or Wi-Fi, pre-loaded Adobe Flash, 16GB internal storage and a slim frame. It has a dual-core 1 GHz processor, 1GB of RAM and runs on the Android 2.3.4 Gingerbread operating system.

It comes with the cloud-friendly app Zumocast, which lets users bring videos, music, pictures and documents stored on their computers to their handset via remote access. In the U.S., the Droid Bionic is available for $299 on a new two-year contract with Verizon or $599 at full retail.

The smartphone from Motorola measures with 127.5 x 66.9 x 11 mm and weighs 158.8 grams. It has a 1 GHz dual-core TI OMAP4430 processor, ULP GeForce GPU and Tegra 2 AP20H chipset with 1GB RAM. It sports a 4.3 inch (about 256 ppi pixel density) 960 x 540 pixels TFT capacitive touchscreen. The smartphone features qHD support, which is a quarter of the full HD resolution.

Additionally, the device has a Li-ion 1735 mAh battery, offering upto 10 h 40 min of talk time. Recent tests suggest that the phone could last for upto 8 hours on 4G LTE, which is a big advantage for this device, given that previous phones using LTE support faced issues with battery drainage.

Also, for users who want to take full advantage of battery power, there is an optional battery support being released for the Droid Bionic with whopping 2760mAh battery. Some users have reported that even with some data consumption and heavy use, the battery managed to last 24 hours.

Motorola Photon 4G

The Motorola Photon 4G, available on Sprint's networks, was launched on July 31 and is priced at $199 with a two-year contract. Motorola introduced the Photon 4G, its second 4G smartphone after Atrix 4G, which revolutionized the market with its laptop docking capabilities.

The Photon, with a dual-core processor, is a world phone that allows users to have international GSM roaming so that they can access their email, calendar and contacts from anywhere.

The Photon 4G is Sprint’s seventh Sprint ID-capable handset. The Sprint ID delivers a number of applications, shortcuts, widgets, ringtones and wallpapers. The pack provides free-to-download goodies under its Everything Data plan and users are allowed to download five packs at a time.

The Photon 4G, which runs on Android 2.3 Gingerbread OS, measures 126.9 x 66.9 x 12.2 mm and weighs 158 grams. It comes with a 1GHz NVIDIA Tegra 2 AP20H dual-core processor with 1GB RAM and 2GB ROM.

It has a 4.3-inch qHD display with 960 x 540 pixels resolution, a 8 megapixel dual-LED flash camera with 720p video capture, a secondary VGA camera, 16GB internal storage and up to 32GB microSD support. The Photon 4G has Rev.A up to 3.1 Mbps, along with 4G LTE support. It has a Li-Po 1700 mAh battery giving up to 9 hours of talk time.

Reviews of the Photon 4G have been positive. Engadget gave the device a 8/10, saying it comes very close to dethroning Samsung's mighty Galaxy S2 as king of the Android hill. CNET UK also gave the device a favorable review, scoring it 4.0/5 and described it as a Sprint iteration of the Atrix 4G because of similar specs.

HTC Sensation 4G

HTC, the Taiwanese technology giant, rolled out the HTC Sensation 4G on June 15. HTC has wrapped the aluminum frame around the sides, back and even in the small portion of the Sensation's front.

The HTC Sensation 4G has lived up to its name and has continued to receive rave reviews for its incredible performance in terms of good display capabilities, a beautiful design, a good camera and HTC Sense.

The Sensation 4G, which runs Android 2.3 Gingerbread OS with HTC's Sense 3.0 user interface, measures 126.1 x 65.4 x 11.3 mm and weighs 148 grams. It is powered by a 1.2 GHz dual-core Adreno 220 GPU Qualcomm MSM 8260 Snapdragon processor.

The HTC Sensation 4G comes with the S-LCD capacitive touchscreen and offers a resolution of 960 x 540 pixels on a 4.3-inch curved high-resolution qHD Gorilla glass display. It also has the customary 8 megapixel dual-LED flash camera with 1080p HD video recording capabilities and a VGA front-facing camera for video calling. The phone sports a 768MB RAM and 1GB internal memory with support for microSD up to 32GB.

HTC’s phone will have T-Mobile’s HSDPA 14.4 Mbps and HSUPA 5.76 Mbps support. It has Wi-Fi 802.11 b/g/n, DLNA, Wi-Fi hotspot support along with Bluetooth version 3.0 with A2DP and microUSB version 2. There is a Li-Ion 1520 mAh battery found in the Sensation 4G which offers up to 8 h 20 min of talk time.

HTC EVO 3D

The HTC EVO 3D is the first glasses-free 3D smartphone, which makes the phone a very special one. It is the successor to the original HTC EVO 4G, which was, probably, the first smartphone to every truly test the iPhone.

The HTC EVO 3D, which runs on Android 2.3 Gingerbread OS, measures 126 x 65 x 12.1 mm and weighs 170 grams. It is powered by a 1.2 GHz dual-core Adreno 220 GPU Qualcomm MSM8660 chipset processor.

The smartphone comes with 4.3-inch qHD 960 x 540 pixels 3D LCD capacitive touchscreen display. It has common input features like accelerometer sensor for UI auto-rotate, multi-touch input method and proximity sensor for auto turn-off. It also comes with HTC Sense's latest version, touch-sensitive controls and Gyro sensor.

The camera found in EVO 3D is a 5 megapixel 2560?1920 pixel device, featuring autofocus and dual-LED flash, Stereoscopic photos (2 megapixel only) and videos and a 1.3 megapixel secondary camera. The EVO 3D captures video of 1080p at 24fps (2D) and 720p at 30fps (3D).

The device has 1GB RAM and 1GB of internal storage. It supports HSDPA 14.4 Mbps and HSUPA, 5.76 Mbps on Sprint's network. It has a Flash-enabled web browsing experience that takes advantage of the speed of the Sprint 3G/4G network.

There is a Li-ion 1730 mAh battery found in the EVO 3D which offers upto 7.5 hours of talk time. It has Wi-Fi 802.11 b/g/n, WiMAX 802.16 e, DLNA, Wi-Fi hotspot, Bluetooth version 3.0 with A2DP, EDR and has microUSB version (MHL) 2.0. Extra features include TV-out via MHL A/V link, MP3/AAC+/WAV/WMA player, MP4/Xvid/H.263/H.264/WMV player and Picasa integration.

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