The time has come for me to choose a new mobile network! I'm currently using Tesco Mobile as the coverage was excellent where I used to live. I was also led to believe that the coverage of most competing networks was poor in the location where I now live, so Tesco or O2 (the former uses the latter's network anyway) seemed the logical choice and I took out a 12-month SIM-only contract.
Orange UK, O2, Vodafone, Hutchison 3G and T-Mobile. MVNOs piggybacking on some of these networks are, among others, Virgin Mobile (on T-Mobile), Tesco Mobile (on O2) and Asda Mobile (on Vodafone). They all provide different levels of coverage in the various locations that I frequent and different levels of service.
The primary concern when choosing a network has to be coverage and service levels, with the deals being offered by the networks only your second consideration. There's no point in getting boatloads of inclusive minutes, more texts than you can use and gigabytes of mobile data at a bargain price if you don't actually have any coverage in the places where you spend most of your life and therefore can't use those minutes etc.
At my workplace I get full 3.5G coverage on all of the major networks so that part isn't even a consideration. At home, things are a little different.
Unfortunately I have to rule out Vodafone (and therefore Asda) because I have absolutely zero coverage at home. Neither 2G nor 3G. Nada. Zip. If I had a contract phone on Vodafone I'd be very unhappy as it would be absolutely useless as anything other than a paperweight.
O2 (and Tesco) provides limited coverage here. I get a weak 2G signal on about half of the ground floor. On the first floor I get a stronger 2G signal in most rooms and a reasonable 3.5G signal in a couple of spots. There are still a few spots where I get no reception at all, which is why I'm looking at alternatives now.
Hutchison 3G would be a good solution if it weren't for two severe drawbacks. Firstly, Three UK is a 3G only network. While they used to have agreements with Orange UK to use their 2G network in areas where there is no 3G coverage from Three, this is no longer always the case. If you're in a zone that's not covered by Three's 3G network, you therefore have no coverage at all. Secondly, and this is something that I remember experiencing with a friend who was on 3 at the time (and with his sister who has just switched away from 3 for this specific reason), text message delivery to handsets on 3's network is sometimes rather random. They just don't always get through. While nobody in their right mind should rely on text messaging for important information, it's still extremely annoying not to receive messages and simply not know about it.
Three UK is therefore out of the equation.
That leaves me with T-Mobile (or Virgin) and Orange. Essentially, they're the same network after their merger in late 2010, which resulted in the creation of "Everything, Everywhere". Not only do they share their 2G networks, but they both can use Three's 3G network in the absence of 3G coverage under the umbrella of Mobile Broadband Network Ltd., a 50/50 joint venture between Three UK and Everything, Everywhere.
These networks give me reasonable 3G or 3.5G coverage almost everywhere on the ground floor. In the few areas where I don't get 3G or better, I do get a usable 2G signal. On the first floor I get 3G or better everywhere. If I force the phone to GSM mode then I still get good 2G or EDGE coverage.
As I understand it, Virgin Mobile does not manage the network switching in the same manner as T-Mobile despite being a MVNO piggybacking on the same physical network.
That leaves T-Mobile and Orange, and I'm leaning towards the former because the SIM-only deals that they're offering do seem to match my requirements better than those from Orange.
My 12-month contract with Tesco is up in June. I'm going to keep an eye on the operators' offerings between now and then in order to choose the one that suits my needs best of all.
Update 26/03/2012: I had a closer look at the plans from Orange and found one that suits me fine, so the deciding factor was the fact that, unlike T-Mobile, Orange supports twitter's SMS gateway. I'm getting 300 minutes, unlimited texts and 500MB of data (tethering allowed!) for £10.50 a month. To that I added a further 500MB for an extra £5/month.