www.travelrants.com writes about the shock impact of mobile phone roaming rates has on International travelers:

It is all well and good owning a mobile phone with GPS, tons of travel apps, but when it costs you £3 – £5 per MB to use the internet abroad, it becomes expensive very quickly. Last week I used my phone in-flight, while jaunting around New York and I have arrived home to a £60 bill for roaming charges.

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The BBC also wrote about this earlier this year:

If you use your phone in the UK to connect to the internet, for example to check emails or go on Facebook, you don’t usually need to worry about the bill – most home tariffs include unlimited downloads.

But, if you take a smartphone, like an iPhone, on your travels, it can have expensive consequences.

One German man was reported to have been charged £41,000 after downloading a television programme onto his phone.

Julia Feuell, from north London, also got a shock after a visit to New Zealand. Her 17 year-old son racked up a bill of £590.

If you’re creating iPhone apps,  it’s critical that your app doesn’t have an expensive network dependency. If it can’t run in “Airplane Mode”, it doesn’t work for travelers (and you’re missing out on other great benefits).