PC to PC Free Internet Phone Software

With a free VoIP software downloaded on your computer, you can make free calls over the internet. This technology is similar to the capability to send instant messages or to send files to one another from their computers via the Internet at no cost.

Skype

Skype lets you make free calls over the Internet. It's free to download and you can add on voicemail for a weenie fee. Skype is available for WIndows, Linux, Mac OS X and Pocket PC platforms. The main difference between Skype and other VoIP clients is that it operates on a peer-to-peer model rather than the more traditional server-client model.