Setting up VoIP system at home

Hello,

I would like to do a small project whereby I set up a end-to-end VoIP softphone system at home (probably between two PCs, or a PC and laptop). My idea is to tinker around with packets and try to implement some algorithms at a packet level (VAD/SS, RTP header compression). I’ve got little clue what I’ll need to enable this (from hardware or software point of views) — I’m starting from scratch.

Hardware: home network, microphone, speakers
Software: SIP agent (WinSIP), …?

My hope is that I am able to find some open-sourced material for a Windows environment. I know that vovida.org has everything I need (although, I’m not sure what I need) for Linux.

Can anyone provide some direction or suggestions? Any ideas on where I can find algorithm resources on VAD/SS and RTP header compression or if there are packages out there that do this?

Greatly appreciated!

Thanks,
Kevin