Next to the pier on Aruba and Curacao you could find phones for international calls with credit card. No information about rate or rules, just instruction for dialing. I needed to make very fast call, so I decided, that even if it is not very cheap, I could call for 1 min (I guessed the rate could be several $/min, maximum 5; from the ship we could call for $7/min). So I called to Canada from Aruba using AmEx, talked around 45-50 sec. The next day I needed to repeat call, so I called from Curacao from the similar phone and again talked about 1 min.
To my surprise and outrage, in AmEx statement I found two charges US$40 each. When I tried to call AmEx and open dispute about these charges, I was told after they talked with the call provider, that they are not able to do something, as this company charges $40 per first 5 min irregardless how much you talked and even in case you just got answering machine. Again, in no place any information was given about it, not nest to phone, not during dialing.
After that in the other forums I found complaints of people, who was also caught with this fraud (they phoned not from the pier, but from airport).
So be cautious to call from phones, where you haven't given rate information, don't take as granted any reasonable charges. Pass this information to your peers.
The same information I'll put in forum Aruba.