Deciding which calling card is cheapest and most convenient depends on which countries you are visiting and the countries you are calling. When calling back home, say to France or Germany, it's usually cheaper to get a card from France Telecom or Deutsche Telekom, especially if it is billed to your home or office account where you may be able to pick up discounts. But look out for exceptions. When calling to third countries, or within a region such as Europe or Southeast Asia, you may find it cheapest to use a calling card issued by a telecom company in one of the countries. The cheapest way to phone within a foreign country is to use a local pre-paid phone card or cash at a pay phone.
Charges can be competitive with major calling cards.