The big four, briefly
The UK has four networks that actually own mobile infrastructure — EE, O2, Vodafone and Three — plus dozens of MVNOs (mobile virtual network operators) that run on top of this infrastructure under different branding and pricing.
Coverage
EE has generally led on outdoor population coverage in independent testing and was the first UK network to launch 5G, giving it the longest track record of 5G rollout depth.
O2 and Vodafone both offer strong, broadly comparable coverage across most of the UK, with occasional regional differences depending on exact location.
Three has historically had the smallest physical network footprint of the four, though its coverage has improved significantly with 5G investment, and it remains genuinely strong in most urban areas.
Why network choice often does not mean choosing EE/O2/Vodafone/Three directly
Many of the best-value SIM plans run on these same four networks through MVNOs — smaller brands that lease network capacity rather than owning it. Mozillion runs on EE, giving EE's coverage at a lower price point than EE's own retail plans. 1pMobile and Ecotalk both also run on EE. This means you can often get EE's actual coverage without paying EE's brand premium.
How to actually choose
Rather than picking a network by reputation alone, check coverage at your specific home and work postcodes using each network's own coverage checker — national averages can hide meaningful local differences. Once you know which underlying network covers you best, compare SIM-only deals from both the network itself and any MVNOs running on it, since the MVNO route is very often the same coverage for less money.
Compare SIM only deals across all networks →