Two out of three holidaymakers are risking high overseas phone charges by leaving their mobile switched on, according to a survey.
Mobile users are charged not just for making and receiving calls but also each time a voicemail message is left and each time a message is picked up.
And more than one in four Brits (43%) have been shocked by an expensive phone bill on their return from holiday, according to the uSwitch.com survey of 1,310 UK adults.
The survey, carried out last month after the introduction of new EU pricing guidelines, found just 4.5% of holidaymakers protect themselves from charges by turning off their phone and keeping it turned off until they need to make a call. Two out of three people (66%) risk high overseas charges by switching on their phone without even intending to use it, with half of those having it turned on most of the time.
Steve Weller, communications expert at uSwitch.com, said: "As soon as your phone is switched on abroad the damage is done - it is registered to a local network and starts to incur overseas charges, even if you switch it straight back off again. This means that you pay to receive calls, make calls, for people to leave you a message and to pick up that message - all at higher overseas rates.
"If you are one of the 27% of people who only take their phone with them in case of an emergency, you are better off switching your phone off in the UK and leaving it switched off until you need it. This way any voicemail messages are being charged at UK rates.
"Failing that you should always tell friends and family to only send texts - which are free for you to receive - or you could ask your mobile phone company to switch off your voicemail service while you are away."
Of those questioned, 42% did not know they could be charged for someone leaving them a voicemail and 10% did not know they could be charged for picking up messages, while 85% were not sure what they were being charged for calls and texts.
The EU guidelines, which came into force on July 1, say the maximum a mobile phone provider can charge for services in Europe is 37p per minute to make phone calls, 16p per minute to receive phone calls and 9p to send a standard text message. Receiving text messages while abroad is free.
Mr Weller said: "For those who prefer to chat, ask your mobile phone provider about a separate roaming package for calls before you travel, or buy an international SIM card that lets you make cheaper calls abroad. This is a very easy step to take but half of us (50%) have never asked about roaming packages and 75% have never used an international SIM card."
