Service claims to offer free international calls. What's the catch?

[cthorpe]

I don't know anyone overseas to try this out, but this site says that they will give you free calls from the US to
Argentina, Australia, Belgium, Brazil (Rio De Janerio), Canada, China, Christmas & Coco’s Island, Cyprus, Denmark, France, Germany, Greece, Hungary, Ireland, Israel, Italy, Mexico, Netherlands, Norway, Poland (Warsaw), Portugal, Russia, Singapore, South Korea, Spain, Sweden, Switzerland, Thailand, UK and USA.

To use it, you call 712-858-8094, then dial the number you want to call.

It claims:
No Sign-ups
Privacy Guaranteed
Unlimited Calls
No Limit On Call Length
Call from Anywhere, Anytime

http://www.allfreecalls.net/

Here is the blog associated with the site: http://blog.roam4free.ie

[dantheman]

As a Canadian citizen, i am evidently unable to try it out.

Non U.S. citizens may want to check out:
http://www.gizmoproject.com/

Any feedback on either is welcome.