British mobile phone signal is so poor that foreign visitors often enjoy better coverage than local people - despite billions of pounds being invested in improving communication networks.
A report by MPs reveals mobile phone coverage in Britain has not improved significantly since 2014, when the then-government agreed to a £5 billion investment deal with Mobile Network Operators (MNOs).
The agreement pledged to give mobile coverage to 90% of the UK's geographic area by December 2017.
But that target is expected to fall short, with at least 525 so called "not-spot" areas across the country, according to the British Infrastructure Group (BIG) of backbench MPs.
Group chairman Grant Shapps said: "It is unacceptable that areas in Britain continue to have such poor mobile connectivity, and that overseas visitors can expect better mobile coverage than Britons stuck with a single provider.
"The time for excuses from the mobile sector is over. The Government must make a better call for Britain and bring national mobile coverage policy into the 21st century."
David Cameron championed the case for improving the country's connectivity when, while prime minister in 2014, he described the difficulty taking telephone calls from fellow world leaders while on holiday in his beloved Cornwall.
Renewing his pledge to help rural communities in broadband "not-spots", Mr Cameron told the Western Morning News : "This is a really big issue for people all over the country - the 'not-spots'.
"It's not good enough to say here's the mobile coverage for the whole country. You have got to recognise a lot of people are making important calls while they are on the move.
"We do need to improve the coverage of the mobile phone signal.
"As I go down a hill into Polzeath, I know exactly which bit of the road I lose my signal.
"So it is a problem. I know where to go to get a signal, but it can be very frustrating."
The BIG report calls on the Government to request an interim update from mobile operators towards achieving their December 2017 coverage goals.
It also identifies plans to protect mobile phone customers.
The report states: "Consumers are at risk from being hit with large exit fees if they decide to terminate their contract, even if it is due to poor quality mobile service.
"BIG argues that Ofcom should establish a Minimum Service Obligation to define consumer rights. If an MNO fails to deliver a high standard of service, consumers should be able to terminate their contract free of charge.
"These reforms should now be included in the Digital Economy Bill."
A Department for Culture, Media and Sport spokesman said: "We know how frustrating poor mobile coverage can be, which is why we made it a legal requirement for each of the mobile network operators to provide coverage to at least 90% of the UK by the end of next year.
"We are taking further action through the Digital Economy Bill currently going through Parliament, which will give the regulator Ofcom the power to issue hefty fines to mobile phone companies who fail to deliver improvements."