In results that will not surprise UK mobile phone users, the BBC's 3G mobile phone reception mapping project has revealed patchy reception across the UK, including in city centres.
22,000 locations were identified where no 3G signal was available, predominantly rural areas. The worst reception was in Gwynedd, North Wales, followed by Cumbria.
The results show that most people get 3G about 75% of the time, but coverage is far from seamless.
Most cities showed excellent coverage but some locations places quite near some centres where all networks failed to deliver a data connection.
While London experiences generally excellent coverage, locations with no 3G reception near the city centre included East Dulwich, Wandsworth, Holland Park, Leytonstone, Greenwich and Canary Wharf. Birmingham reported excellent coverage, as did Edinburgh and Glasgow.
In July, the BBC asked members of the public to take part in the crowd-sourced survey by downloading an app for Android phones. Respondents were spread across the UK from Shetland to Cornwall.