I felt suspicious at first too, but after trying Voip Stunt I was stunned! They are actually free although as you probably expected, there is a teeny weenie catch.

The catch:
Free calls last for 1 minute unless you have credit in your VoipStunt account. You have to purchase a minimum of 10 Euros (~$14) every 120 days to keep your account active.

In a nutshell:
For $3.5/month you can make free PC-to-Phone calls to the following countries:
Andorra, Argentina, Australia, Austria, Belgium, Bulgaria, Canada, Chile, China, Colombia, Cyprus, Denmark, Finland, France, Georgia, Germany, Gibraltar, Hong Kong, Hungary, Iceland, Ireland, Italy, Japan, Latvia, Liechtenstein, Luxembourg, Malaysia, Monaco, Mongolia, Netherlands, New Zealand, Norway, Panama, Peru, Portugal, Singapore, Slovenia, South Korea, Spain, Sweden, Taiwan, Thailand, Turkey, United Kingdom, United States, Venezuela

I personally think that this is one hot phone deal, especially if you make a lot of international calls. Give VoipStunt a try, without buying any credit (and without using your credit card at all), and decide whether it suits your needs.