A , a £20,000 bill – the stories of shock bills when people use their phones overseas are remarkably common.
The frightening thing is that it's not just overseas where you can be slapped by roaming charges – it can happen to you in the UK as well.
In fact, there are several places where using data on your phone means hefty charges that you can travel to without leaving the country.
“The Channel Islands and the Isle of Man have their own mobile networks, which means visitors from the UK mainland will be vulnerable to roaming charges if they use their phones there,” Ernest Doku, telecoms expert at , told The Mirror.
“You can’t blame people for thinking the Isle of Man and the Channel Islands are covered by mainland UK networks. There’s a lot of expectation on consumers to know the rules when it comes to roaming - and these can be really confusing.”
Then there's “inadvertent roaming”.
That's where your phone picks up a foreign network without you ever leaving the country.
“Some mobile customers in Northern Ireland who live near the Irish border have been hit with bigger bills due to so called ‘inadvertent roaming’,” Doku added. “Their mobile connects to a mast in the Republic of Ireland and so they are charged roaming rates.”
Worryingly, this isn't just a problem in Northern Ireland. There have also been cases reported in Dover and on the south coast of England where .
To protect against this, especially in the UK, the best advice is to ensure you're signed in to your own network.
Typically, this won't change unless you lose signal entirely or turn your phone off or on. If you sign in to a non-standard network you're generally sent a text message by the new provider – so watch for these and make sure you pay attention to them.
If you find yourself signed in to an overseas network, try turning aeroplane mode off and on again to see if you can re-connect to your home network.
If that doesn't work, you should be able to manually select your own provider from the “network settings” in your phone's menu.
Of course, if you're in an area not covered by your home network, your best option is to act as though you're abroad.
There's some good news here – firstly, the amount you can be charged for roaming in the EU is capped. – just not yet.
“Unfortunately, the EU has just voted to delay scrapping these charges,” Doku told The Mirror.
Mobile data spend is also capped by by UK networks to protect, but that still leaves people losing out. In the past year, one Brit in five has come home from an EU holiday to find their bills an average of £61 higher than they expected, uSwitch figures show.
To cut the cost overseas, you are recommended to turn off mobile data on your phone, and possibly contact your provider to switch off data roaming entirely.