What do the HTC Evo Shift, the Motorola Atrix and the Samsung Infuse all have in common? You get one point for answering that they were all announced at CES 2011 but spotting that they're all 4G phones is how you claim the cigar.

You've probably heard the term 4G thrown casually into conversation by mobile phone aficionados, but what does it actually mean? In simple terms, 4G refers to the fourth generation of wireless technology networks and follows on from 2G and 3G.

While 1G refers to the first batch of widely available handsets; 2G switched to a digital system, bringing with it the introduction of text messaging; then 3G technology offered huge improvements, not least the possibility of easy web browsing and now 4G has been developed to cope with the rate requirements set by further evolution of existing 3G applications like text messaging, video calling and mobile TV.

In short, all the improvements that have been added to your fancy smartphone, such as HDTV capability, need more advanced technology and more speed, and the 3G network simply won't be able to cut the mustard indefinitely. 4G is the answer to that problem.

Up until recently, 4G has been used as a catch-all marketing term for the next generation of mobile services as until October 2010 there was no definitive, industry-set criteria for what constitutes a 4G network. The ITU (International Telecommunication Union) only recently made things official and that meant that none of the the so-called 4G networks available in the US or elsewhere in the world officially qualified.

No doubt ruffling a few feathers among the networks, the ITU states that there are now only two major technologies in development that can be classed as 4G - LTE-Advanced and WiMax 2 - both of which are enhanced versions of what carriers currently describe as 4G and both of which are unlikely to be rolled out until later at least 2012. Whether this next generation of technology will eventually end up being known as 4.5G or 5G, remains to be seen. So, as it stands, what we're actually being sold as 4G at the moment isn't exactly true to the term.

According to the ITU - a UN agency that regulates information and communication technology issues and coordinates the shared global use of the radio spectrum - there are various standards that true-4G networks will need to offer in the future. Only those that meet these will be awarded the status of IMT-Advanced (International Mobile Telecommunications Advanced) and in turn, the title of 4G. The list of requirements declares that a 4G network must be able to exchange data at a rate of up to 100 Mbps. To put that into perspective, data speeds on a 3G network can currently be as slow as 3.84 Mbps, so it's a considerable leap.

Despite not meeting the ITU's strict standards it seems fair, in practical terms, to call the current 4G-branded offerings 4G as they offer substantially faster connections beyond that which 3G currently gives us, and it looks like the operators will continue to use this distinction, whether it's technically correct or not.

The benefits for 4G users - in either sense of the term - mainly come down to internet speeds, so if that's not an issue for you, then you probably don't need to worry just yet. The greater capacity offered by 4G means that it can be used for internet access on home computers, without the need for cabling. If you're sick of the data limits that are imposed on you by your ISP, then you'll be pleased to hear that there are currently no bandwidth caps and speed throttling on the 4G networks in commercial use. Having said that, we would imagine that caps will be introduced at some point in the future once there are more users on board, although they should be significantly higher than anything on 3G. Until then, you'll be able to use as much bandwidth as you like so that you can maintain high speeds without your ISP having to slow you down.

Mobile networks in the US are currently using different technology from one another to make 4G possible (or what everyone is calling 4G, despite the ITU's new criteria) . While Sprint uses WiMax technology, Verizon Wireless uses Long Term Evolution (LTE for short) and T-Mobile offers HSPA+ - a 3G technology with 4G speeds. Verizon will support up to 5-12Mbps and Sprint's WiMax can reach a headline offer of 3-6Mbps, in comparison with the maximum 100Mbps that will be required from true 4G networks.

The services are currently limited to urban areas but Verizon recently added another 49 US cities to its 4G coverage map, taking the total for 2011 up to 102 with the carrier promising nationwide coverage by 2013. The first handset to be available on the network will be the exclusive, US-only HTC Thunderbolt. Four smartphones, two tablets, two netbooks, and two MiFi hotspots are expected to be available before the summer.

As for the cost, there's two data plans at present - $50 a month for 5GB, or $80 for 10GB (with the network promising no speed throttling) - and, if you want to use more data than your monthly limit, then you'll be charged a pound for pound extra $10 per 1GB.

As for Sprint, the network is gradually increasing its 4G offering and states that its WiMax system currently covers more than 40 million possible people. Naturally, all of them aren't actually using it. Sprint puts WiMax at around 2.5GHz on the spectrum, which isn't too far from where 3G sits in the UK so, in theory, it should have a similar kind of coverage from each mast.

Operating on similar principles to Wi-Fi, WiMax can cover distances of up to 30 miles. As with all wireless technologies though, WiMax can operate either at higher bitrates or over long distances, but not both. Operating at its maximum range of 50km (just over 30 miles) will result in a much lower bitrate, so lowering the range means higher possible speeds

As with Verizon, there are currently only a couple of modems available, along with the Samsung Epic handset, but more products are on the way soon including the HTC Evo 4G. Sprint is offering unlimited 4G for $60 a month (but 3G capped at 5GB, if you find yourself in an area with no 4G coverage). It also sells a 4G day pass for just $9.99.

So that's the state of play for those lucky early adopters o'er the Pond but when can we expect to see 4G in the UK? Ofcom has just unveiled plans for the UK's 4G auction, with the spectrum sale due to start in Q1 of 2012. According to the independent regulator, the additional space that will be freed up for 4G makes up 75 per cent of the current mobile spectrum and is 80 per cent more than the space that went under the hammer during the 3G auction in 2000. The 4G spectrum will comprise two bands - with the 800 MHz frequency becoming available thanks to the analogue TV switch-off and the 2.6GHz section offering high speeds for all your HD-laden mobile devices. The auction will be split into five 'spectrum floors' so that all of the big networks will be able to throw their hats into the ring, while they'll be a couple of safeguards in place to keep things fair and make sure that none of the operators gain an unfair advantage.

In theory, this means that the UK could see 4G services as early as 2012. We know that testing has already been carried out, and it's likely that there'll be localised consumer trials before the big roll-out, although in reality it's likely that we won't actually see a nationwide 4G offering in place and available to the public until 2013. Until then, we'll just have to dream of that faster mobile connection.

This article was first published on 18/01/2011.

What do you think about 4G services? Are you itching to get a go and what do those in the US make of the service as it stands? Let us know in the comments box below.