With many of the best smartphones available on all the UK networks, we've been taking a look at what makes a mobile operator a good one beyond the headlines of just stocking an Apple phone. We've examined roaming charges; the range and quality of handsets on offer and even some ideas on how to get the best coverage of your life but today is the chance to look a little broader and see why the choice of network is really just as, if not more, important than your choice of phone.

Talk to the mobile operators and they'll tell you about the three Cs of phone networks - coverage, capacity and consistency. You can also throw in speed as well but it's largely a function of coverage and consistency combined with the available technology and how dedicated you are at making sure the best of the best has been deployed.

Coverage is the one that everyone understands or has certainly heard of. When you're wandering around the British countryside holding your phone high up in the air in desperate search for just one little bar of reception to make a call, it's coverage that you crave. Either you're in a geographically very tricky location or, more likely, your mobile provider just doesn't have any masts anywhere near where you are. As a user there's very little you can do about that apart from remember next time to choose a provider that has more, or different, mobile sites.

There's a few things to bear in mind if you're shopping around for the best coverage. The first is that networks tend to quote their coverage as a percentage of the UK's population that they're able to serve rather than a percentage of geographical spread. So, figures of 98.5% coverage are not necessarily as impressive as they sound given that the overwhelming majority of the population live in towns and cities and, just because you don't live in the countryside, it doesn't mean you won't feel that frustration when you visit there. So, the best thing to do here would be to consult coverage maps of the UK or try to find out figures of geographical coverage from the networks.

There's also a further trick that you need to watch out for when you're looking at the maps as well as reading the figures. Some networks will quote outdoor coverage reception, which is easier to achieve, rather than indoor coverage which can be tricky in both the concrete and steel packed cities and the sparse areas of the country. 3 is one of the better networks here who actually show both indoor and outdoor zones on its maps.

Radio Frequency
One of the major factors that effects the difference in quality between indoor and outdoor coverage are the radio frequencies which mobile masts transmit on. There are two GSM frequencies that the UK networks are allowed to use for their 2G connections - 900MHz and 1800MHz. While a higher frequency might make for a more intense signal, it's the lower frequency that will travel further and have better penetration as well. So, mobile masts transmitting at 900MHz are going to mean that you don't have to be as close to them to get a signal and that you're more likely to get reception while indoors.

The plot thickens when you find out that it's only Vodafone and O2 in the UK that are licensed to use both 900MHz and 1800MHz. Orange and T-Mobile only have 1800MHz to play with. Virgin Mobile uses the T-Mobile network, so there's no joy there; Tesco Mobile uses O2 and 3 has an agreement with Orange for 2G coverage. So, with Vodafone, O2 and Tesco Mobile, you've already got an advantage just by signing up with them.

Of course, the others can get round this by deploying more mobile mast sites, but then that's money that they could be spending on improving other areas of their network or making bids for exclusive handsets or just to offer more competitively priced contracts.

Thankfully, with 3G, everyone's in the same boat as it works at 2.1GHz but the high frequency used does also help explain why it's even harder to have nationwide 3G reception. It should be noted when choosing your network, though, that 3 and T-Mobile have the best 3G network coverage in the UK. The two share the same 3G infrastructure.

But the sad truth about coverage, and certainly 2G coverage, is that there's a good chance it's not going to get much better in the near future. It's unlikely that many mobile networks consider it economically viable to spend money on building individual masts for each 10-man, 3-dog hamlet in the Highlands to get a signal. Business-wise it just might not be worth their while. Whether 3G will get as big a national spread as 2G remains to be seen.

If coverage has you divining for signal, it's capacity that you can blame when you get that "Network Busy" message popping up on your screen. Capacity is a function of how much bandwidth each mobile mast has to play with. Although we talk about frequencies of 900MHz and 1800MHz, what's actually being referred to is a portion of the spectrum around those numbers - 890MHz or so and 910MHz, for example - and the networks get this divvied up between them.

Users occupy this bandwidth while making calls, so if everyone on your network makes calls at the same time, there's not going to be enough bandwidth for everyone to work with and that's when people are told that the network is busy. You have a capacity problem. The classic example is trying to make a call at a gig or a football match at half time. Some networks, like Vodafone have special event teams that run around with portable mobile masts to help at big occasions. So, for good capacity, you want your network to not just have enough masts to cover the area but enough to serve a population as well.

The concept of contiguous spectrum is another factor for capacity. The sections of spectrum allocated to each of the providers is not necessarily in one large block. More often, it's cut up into smaller chunks dotted about the range. Because no one wants interference from neighbouring operators working on neighbouring bits of spectrum, they have to create dead zones at the ends of these chunks of spectrum called Guard Bands. They ensure that there's no bleed from operator to another.

Now, obviously guard bands reduce your capacity as they're perfectly good bits of spectrum that you have to leave neutral. So, if you had one massive chunk of spectrum, you'd only need to waste bandwidth on two of them. If you have two chunks, then suddenly you'll need four and your capacity losses will double. So, the more contiguous spectrum you have, the better your capacity can be. This could well be a big issue when the T-Mobile and Orange merger takes place with the two networks combining whatever spectrum at 1800MHz that they have to create sections of bandwidth larger and more contiguous than anyone else's. Should this go ahead unchallenged, then they might make a good choice of mobile provider in the future, particularly combined with T-Mobile's 3G prowess - should the partnership agreement with 3 continue, of course.

Capacity is a massive issue as far as smartphones go because bandwidth is so varied and so important when trying to use the Internet on your phone. It might be all very well if 100 users of a single network are trying to read their e-mails at the same time, but if they all want to stream HD video, then there's going to be much more of a strain. While speeds of 7.2Mbps might be advertised, this is soon cut down to much less if you're having to share bandwidth with a lot of other people.

There are no real ways for the user to get around capacity issues. You just have to hope that your provider has quality of service in mind and that they haven't scrimped on 3G mobile masts where they have a lot of subscribers. If their threshold of when it's time to put a new site in is too high, then it doesn't matter if you have the best browsing phone in the world. It'll chug along like it's on dial-up.

The final C is consistency and it's all about having regularity of service. Any time you're on the phone with both parties in apparently good areas of reception and the call is dropped, the chances are it's because there's consistency issues.

Generally speaking, consistency issues have very little to do with the mobile masts. They should be of a good enough quality to work 99 per cent of the time. The issues are in the back-haul - ie how these masts get their information to the core network of the mobile provider - and the core network itself. While most networks should be clued up enough to connect all their masts together in such an arrangement that there are fail safe ways of conveying the information back home, not all of the core networks are on equal footing.

There are all sorts of different ways and means you can plan and engineer your core network to work more efficiently but probably the most effect method that's been done so far and the most unique in the UK is the 3-year overhaul that Vodafone has just applied to its centre. Rather than have two separate core networks to crunch all the data and connect all the lines as all other providers in the UK - one for 3G and one for 2G - Vodafone has combined theirs into a single core network.

The upshot is that you get a much smoother, far more reliable system of operating. One of the big problems for operators since the arrival of 3G has been the issue of switching phones when users move between areas of 2G coverage and high speed 3G coverage. Because the call has to be switched, what often happens is that this call is dropped. Another problem when not on calls is that a user's mobile might become what's called a "sleeping phone" and simply fall off the network for hours at a time after it unsuccessfully moves from 2G to 3G area or vice versa.

So, when it's time for you to renew your mobile contract, you might want to have a little read around to see if yours or any others you're looking at are planning on doing some serious upgrading to their systems.

There are, of course, plenty of reasons to choose one mobile network over another. With all the glitz and glam of exclusive handsets that do the washing up for you, free broadband deals or providers offering to throw in a PlayStation for free, just remember to think about the actual state of their networks as well. If your phone doesn't work as much of a phone, then exactly what is it that you're carrying around in your pocket?

Vodafone UK is the smart choice for customers who want to make the most of smartphones, according to the latest pieces of research from YouGov.

YouGov’s Technology & Telecoms Consulting team’s latest survey, Smartphone, Mobile Internet, eXperience (SMIX), positionsVodafone UK as the top operator for mobile internet, coming top in 8 out of 10 areas and beating its rivals in the most important measure of quality – reliability during the day.