Recently we were updating the Roaming Zone pages to include rates and capabilities for US phones to roam in Canada. It also gave us the chance to update our International and Mexico roaming pages. We noted the usual roaming rates, international plans and foreign roaming capabilities. One surprise: data roaming rates can be unbelievably high. Often there were no 'packages' for data roaming. T-Mobile charges as much as $15 per MB for foreign data. And even if you find a good rate, rounding up increases your effective cost for small quantities of usage.
Some users who don't take advantage as sites like ours have been known to receive roaming charges in the thousands of dollars, and one unlucky T-Mobile customer got a roaming bill for over $200,000!
Domestic data roaming charges have also been a problem but the FCC is keeping those fees more reasonable. Outside the US...the sky's the limit! Unless you know your rates in advance, or you have a roaming data package, consider turning off your phone's Data capabilities before leaving the US. At least check the International Roaming Considerations and keep that nasty surprise from your vacation nothing more than a sunburn.