You probably don’t use them much, since technology now allows us to make international phone calls through computers.
However, if you consider buying a phone card, you want to know that reports have claimed that the average pre-paid cards offer only 60% of the minutes they claim they do, meaning a large scale fraud of over hundreds of thousands of dollars a day.
How to avoid: if you need to use a long distance phone card, either buy it directly from the telecom company or from a post office.