There are four main networks in the UK: Vodafone, Three, EE and O2. You can use our Cheap Mobile Finder to filter networks if you know a certain network has better coverage in your area.
There are also smaller networks which piggyback of the main networks. These are known as mobile virtual network operators (MVNOs). These are separate from the big providers, but have agreements in place to use their networks, so this can be a good way to save if only one network has good coverage where you are. An example would be Giffgaff, which uses O2's network to operate its service. More examples include Voxi (uses Vodafone), Tesco Mobile (uses O2), Virgin Mobile (uses Vodafone) and Smarty (uses Three).