Dialstation: call-from-your-mobile-phone project
In beta and offers free 20-minute call. Haven't started using the service though, but could perhaps be worth looking into.
The following is part of the blurb:
Not only do you get some free credit when you first try Dialstation, but we also credit your account whenever somebody calls you on Dialstation! Every person you call will receive 20% of the value of the call as a credit in their Dialstation account. Another reason they will be glad you called!
Dialstation is a product of Telekommunisten, we seriously care about the world we live in. We are anti-war, against corporate globalization, and against racism and inequality.
We are a 100% worker owned and operated technology company. Every cent you spend on Dialstation contributes directly to the service you receive and supports the work we do.