I heard that if you somehow combine Skype with another program, you can make free unlimited out-going VOIP calls to landlines. Please tell me what that software is and how I link that with Skype. (or if you know a free unlimited VOIP program, let me know) Thanks

Apart from technical details of soft voip, I also want to know how to set it up on my home pc.

I am in the UK, my mum is in Australia. I want to call her over the internet. Skype is really poor quality. She is already on a VoIP service called MyNetPhone. I would like to chat to her for free or cheap. Any ideas?