Sorry, this will be a bit of a rant. There's so much to consider that's happened alongside this, such as reallocation of frequencies within 4G networks to 5G, and the rollout of 5G Standalone (some describe it as 5G+) which doesn't rely on combining 4G and 5G. 3G remained a very useful layer of coverage, especially in rural areas, as it generally seemed to travel further than 4G, but also because most phones would try to cling to 4G for longer leaving 3G empty. I'd sometimes use it at large scale events because it'd be totally uncongested! The effect of removing 3G has been that areas of poor coverage will now drop to 2G, which is basically unusable as a data connection these days, or it'll cling to poor quality 4G which is prevalent in the UK. I don't think just the removal of 3G can be blamed for everything, but rather the UK as a whole has a fundamental and systemic issue of failing to invest in its mobile networks because, as a market, everyone is very price sensitive. Running a mobile network becomes a race to the bottom, with networks undercutting each other on pricing to the point that they can't spend money on the network improvements they need to be functional in modern society. The railway also has various issues with mobile coverage too, with a lack of RF-transparent glass you'd see in other countries (or on EMR's new Class 810s), and a lack of on-board signal repeaters (used to exist on VT's 390s and 221s, but were removed in the early 2010s). I've actually been working on a project for the last few months that collects real-world mobile signal metrics on the railway to predict how poor someone's experience will be on a journey. Lots of other replies have been saying some networks are better than others, but so much of that is subjective, and location dependent. No-one is objectively better. Three and Vodafone are slowly merging their networks, so they might have be bad individually, but now they're fairly good, but soon they'll be turning off many of their sites to cut costs post-merger and they may well turn bad again! I always get rather amused when people say O2 or Vodafone is better, when they both actually share the majority of their sites across the country through a JV called Cornerstone Networks.