Many smartphone users travelling overseas have been shocked to return to huge bills, sometimes $1000 more than usual, because of global roaming.
About 300 travel centre agents who used smartphones such as iPhones or BlackBerrys while overseas in the past 18 months were surveyed by telecommunications company Vodafone.
Sixty-four per cent of them said they paid at least $100 over their usual bill when they returned; 6 per cent said they paid more than $500; and 3 per cent said they paid more than $1000 over their usual bill.
The costs of using smartphones overseas forced most users to change their habits but participants said there were some things they could not do without when travelling.
The most popular uses for smartphones overseas were keeping in touch with loved ones, with Facebook overwhelmingly the most popular application, followed by using maps, checking or sending emails and posting travel updates and photos to social networking sites, the survey found.