Please consider a telephone service provider, what is your opinion? - http://www.sociable-cards.com/

I agree with Heinz, there are lots of dialthrough services which provides cheap international calls.

it's a Masterbell/Comfi reseller, so is spam

Some brands would be ok for travelling, I'd go for maybe Continental or FastWorld if I needed one (Bizon seems to be USA only now) but for making calls from home or mobiles here, we can do better

Using callback with certain VoIP providers could be cheaper, though can seem a bit more complicated. The Continental card has callback as well as callthrough

With any calling cards, check all the charges, some but not all have maintenance and other fees