4G promises faster connection to the Internet for high-speed Web browsing, music and video streaming, and uploading pictures and updates. The first 4G network is EE, formerly known as Everything Everywhere, created by the merger of Orange and T-Mobile.
Leaving aside the Lumias and the Note 2, we tested each of the four phones currently available on EE's 4G network ahead of the public launch, and we've also compared the fab four on their other merits. Read on to see which is our pick of the 4G flock.
As the first 4G phones, the most obvious thing to compare is their performance on 4G. If only it was as simple as that...
We tested the 4G quartet with different tasks that involve connecting to the Web, as well as using the Speedtest.net app for Android and iPhone to measure upload and download speeds. We compared the phones against each other as well as a 3G iPhone 5 on O2 and a 3G iPhone 4S.
In our tests, the fastest phone was the Galaxy S3 LTE, which loaded webpages the quickest. In terms of download speed the S3 and iPhone 5 both performed best, scoring above 40Mbps a number of times. The S3 was more consistent, however, with the iPhone 5's speed more likely to drop drastically.
The Huawei Ascend P1 LTE was next of the four, topping out at 27Mbps and averaging around 15Mbps. The HTC One XL disappointed, peaking at 15Mbps but averaging closer to 10Mbps.
But before the folks at Samsung get too excited, we have to offer a word of warning about 4G tests. These results reflect 4G speeds at that one time, at that one spot, and shouldn't be taken as a definitive demonstration of the speeds you can expect once 4G is open to the public and every Tom, Dick and Harry is watching iPlayer while they're walking down the street.
I should also note that we carried out these tests in central London. We're conscious that the performance of any phone in London is likely to be very different to what the rest of the country can expect, but for the moment our tests have been confined to locations near to EE's office. When we can test outside the capital, we will.
For more on 4G speeds, and why they can't be accurately measured yet, hit play to check out our speed test including the iPhone, S3, One XL and P1 LTE -- and read the results here.
So the jury's still out on 4G performance. But how do the phones measure up against each other in other areas?
Design and build
The iPhone 5's smaller screen is matched by light weight: it's just 112g, nearly 22g lighter than the S3. The iPhone is also a beautifully built piece of engineering, with a gorgeous aluminium casing banded in steel. Unfortunately the black version is prone to scratches round the edge, although the white model is less susceptible.
The S3's clip-on plastic back and blobby camera don't have anything like such a premium feel, and nor does the One XL's featureless rear. But the larger screens give you more room to play with, while the P1 LTE has a subtle chin that helps it sit comfortably in your hand.
The Samsung Galaxy S3 is the biggest of the four, with a whopping 4.8-inch screen. Or if you prefer something a bit more petite, the iPhone 5 has a 4-inch display. Both screens are absolutely gorgeous -- perfect for watching movies, playing games and browsing the Web, all in crisp, clear detail. Which you prefer is up to you: I personally find the iPhone a bit small, and love the S3's slab-like screen; but others think the S3 is too pocket-stretchingly big.
For some reason the One XL has a much lower resolution 4.7-inch screen than the One X on which it's based: the display is 540x960 pixels, instead of the One X's glorious high-definition 720x1,280-pixel display. The P1 LTE is has the same resolution, but crammed into a more dainty 4.3 inches.
The One XL and P1 LTE both boast 1.5GHz dual-core processors, which means they're no slouches. But once again the One XL is a step down from the mighty quad-core chip in the original One X, which was crushed by the original S3 in benchmark tests.
But the S3 is in turn beaten by the iPhone 5. The A6 processor in the iPhone 5 dynamically overclocks, which is a fancy way of saying the chip uses less power when you don't need it, and ramps up when you do. We'd need to do proper benchmark tests to see how the S3 LTE specifically shapes up against the iPhone, but early signs point to Apple's chip winning out.
The iPhone runs Apple's iOS 6 software. That means you get to whisper sweet nothings to voice-controlled personal assistant Siri, download apps from the iTunes App Store, and make FaceTime video calls. But you're also saddled with Apple's controversial Maps app, which isn't a patch on Google Maps.
The P1 LTE, One XL and S3 run Google's Android software. For the average user, the iPhone interface is simpler. But Android lets you customise your phone to your heart's content, and there's a much more open choice of apps in the Google Play app store.
Android also offers widgets and the far superior Google Maps app. And the Samsung Galaxy S3 LTE comes with the latest version of Android, Jelly Bean, which means you're ahead of the Android pack if you opt for the Samsung.
All four phones have 8-megapixel cameras, which should give a level playing field. We focused on exploring the 4G technology rather than testing the camera on each phone, but if you're interested in phone photography, we have compared the original non-4G Galaxy S3 and One X snappers with the iPhone 5 in our photo face-off.
There, the iPhone's HDR mode and decently flash-lit low-light snaps edged out the other phones. However, if you like taking control of your photos, the S3 offers the most features, especially now it's been updated to the latest version of Android, Jelly Bean, in the LTE version.
Remember this is only the first comparison of the first 4G phalanx -- when the Nokia Lumia 920 and 820 enter the mix in November, things may change. Look out for our full reviews of each phone coming soon for more detail on 4G performance.
In the meantime, the HTC One XL and Huawei Ascend P1 LTE are both excellent phones. But this is tale of two titans: the iPhone 5 and Samsung Galaxy S3 LTE. Both are fantastic pieces of kit, each with their own strengths. But in this case, there's one clear winner.
The iPhone 5 is a male model, beautifully put together and a slick all-rounder -- but the S3 LTE is an Olympic weightlifter, a powerhouse of a phone with a giant screen, rammed with Jelly Bean features. It's also, from our first tests, the fastest 4G phone so far.
Which 4G phone is your favourite? Tell me your thoughts in the comments or on our Facebook page.