i-Link is the only thing that i know that does what you want, and it isn't "talking over the internet" either. Basically how it wroks is you put in your phone number, and the number you want to call. It then calls you, and connects your call. The only bad thing about this is that you have to click something every 3 minutes or something. It's all over the web- no software to install, and it really does work... it worked great on the callback payphone at school
Note- I haven't used it in a while so I don't know if there are time restrictions or anything like that, just thought i'd give you an alternative...
-Rivak