While Skype (which I am using extensively these days) makes it easy to call your Internet-using friends for free you normally have to pay something if you want to call a conventional phone using a voice over IP service (BBC hype notwithstanding). One organization, however, is enabling completely free of charge phoning – the fwdOUT Network. The catch is that you have to be running a Linux-based PBX on your own phone (thus enabling others to share your line) in order to participate.
Free World Dialup (by some of the same people) used to offer free calls to a number of locations around the world to anyone using an IP phone but I guess that wasn’t economically viable and it now offers straight computer to computer telephony….
