www.dialnow.com

DialNow offers the lowest international tariffs and is easy to use. Just register an account on their website with your phonenumber and buy credit.

For 10 euro you can call up to 2000 minutes!
To make a phonecall using their service, just dial the low cost access number from the country where you live, followed by the complete international number you wish to call.

* If you need a voucher or credit balances to make pc to phone call, you can buy from resellers.