People in large parts of the UK are unable to access the internet via mobile networks, maps published by industry watchdog Ofcom revealed today.
Increasing numbers of Britons rely on mobile phones, with millions using 3G, or third generation, services to connect to the web using a mobile phone or by plugging a USB modem or data card into a computer.
But the maps show problems affecting rur
al areas, as well as swathes of Scotland, Wales, Northern Ireland, south-western England, northern England and East Anglia.
Ofcom said the graphics provide a "snapshot" view of coverage across the UK on Vodafone, Orange, O2, T-Mobile and 3 mobile networks with shaded areas indicating where customers have the possibility of making and receiving a call outside over a 3G network.
Mostly Mobile, Ofcom's second phase of its mobile sector assessment, was also published today, revealing that consumers are increasingly giving up landlines in favour of their mobile phones and setting out plans to push for improved coverage.
"Coverage of mobile networks in the UK is generally good," Ofcom said. "Indeed, it is better than in other comparable countries, but some issues persist.
"For 3G network coverage there is still a noticeable difference between rural and urban areas, and also between different parts of the UK, with coverage problems a particular issue in the devolved nations.
"Mobile services have become central for UK citizens and consumers and for businesses.
"We have therefore decided that now is the right time to look into coverage issues in more detail."
A range of possibilities can be blamed for the variations, including problems with technology, cost, planning restrictions and topographical factors such as hilly or mountainous landscapes, Ofcom said.
The document added: "Furthermore, the intrinsic nature of cellular technology makes it extremely difficult to provide seamless, 100% coverage across the country.
"Put simply, coverage issues are complex and aiming to solve all of them may be unrealistic.
"However, we do believe that commercially-driven 3G roll-out in particular can still go further than it does today, despite these challenges."
The regulator pledged to push for improvements by focusing on "not-spot" areas with poor or no reception.
Ofcom said it would investigate the causes and work with public bodies to consider how to resolve the problems, carry out research into quality of services provided by mobile operators and help the Government on its proposals to make more spectrum available for mobile broadband and to improve 3G coverage on key transport routes.
Last month, the Digital Britain report set out the Government's objectives for "progress" towards universal 3G coverage and reliable coverage on the rail network and London Underground.
There are more than 76 million mobile phone subscriptions in the UK and more than two million people signed up for new mobile broadband deals between February last year and February this year, according to the watchdog.
Some 85% of adults have a mobile, with people increasingly abandoning landlines.
While mobile phone calls rose by 11 billion minutes last year, the number of minutes on fixed lines fell by 8 billion, new research by Ofcom revealed.
The number of households with landlines dropped to 85% last year from a peak of 90% in 2007.
According to the research, last year there were 1.2 million SIM-only contract sales in the UK, which was equivalent to a fifth of all contract sales during that period.
Usually lasting a month, SIM-only deals combine a bundle of calls and texts with the flexibility of pre-paid services and mean customers avoid being locked into long contracts.
Another trend identified by Ofcom showed people are downloading more data on the move, with data service revenues rising from 1% per mobile connection in 2003 to almost 6% last year.
H3G 3G coverage map
O2 3G coverage map
T Mobile 3G coverage
Vodafone 3G coverage map
Orange 3G coverage map
