While it's never happened to us I have heard of credit cards being frozen due to unusual charges.

It's supposed to be a good idea to call your credit card company/s and make them aware that you will be traveling (which I always forget to do).

If you look on the back of most credit cards you should see a phone number for an International Collect call so if this should happen you can call them to have the card reactivated.

Chris in Pearland, TX