You are in an airport or a train station, in a country that's not your own. You need to make a phone call back home, but you don't have the proper coins. Finally, you find a public phone that takes credit cards. The phone, just like many others, has a sticker on it, informing you: “For international calls, dial "1-800-xxxx".

You follow the directions and make your call. You keep it brief, thinking it'll save you from some of the outlandish charges. But a month later when you finally get your bill, you notice that two-minute call cost you $90!

Scammers will often post official-looking stickers on the phones, advertising their own hot-lines numbers, which they set-up in order to rip off the victims. Several train stations in Rome, Milano, Barcelona, or Monte Carlo are very well-known for this scam.

How to avoid: do not make phone calls using your credit card, especially in tourist cities. Not even if the rates are posted. Get a coffee or a pack of gum to get the change you need.