Ofcom has published maps of 3G coverage for the UK, showing where each operator meets the regulator's minimum coverage threshold.
The maps, published on Wednesday, are not designed to show neighbourhood-level coverage — the sort of detail that is provided on many operators' own sites — and they do not show where 3G users can find the highest speeds.
Instead, Ofcom said they "indicate areas where customers have the possibility of making and receiving a call outside over a 3G network (but with no guarantee of being able to do so)".
The regulator's publication of the maps was welcomed by the Communications Consumer Panel, which pointed out that the maps showed "substantial gaps in mobile broadband coverage", an issue that the panel has identified as problematic for users.
Ofcom announced that it plans to conduct research into mobile-broadband speeds and other quality-of-service issues across the UK. In addition, it will investigate the causes of so-called "not-spots", areas of poor or no reception.
The map shown above represents 3's coverage in the UK. This is the most highly populated map, as 3 is the only operator in the UK that has always had a 3G network.
This map shows O2's 3G coverage in the UK.
It is the most thinly covered map in the series. Ofcom has in the past threatened O2 with a fine for not rolling out its network quickly enough to fulfil its 3G licence conditions.
This map shows T-Mobile's 3G coverage in the UK.
This map shows Orange's 3G coverage in the UK, which appears to be second only to 3's network in its extent.
This map shows Vodafone's 3G coverage in the UK.