MicroSIP is Free VO IP "Voice Over IP" software. It can be used to send and receive phone calls or video calls (Point to Point) for Free by IP address.
Loudtalks Lite is a Free Portable Tool that supports Push to Talk (PTT) Voice Over IP (VOIP) communication. It functions similar to popular software like Skype.
PicoPhone is a Free VOIP Internet Phone application with chat. The author created PicoPhone because most Internet phones use overly complex protocols that can cause problems when used with NAPT routers.
12Voip is free Portable Voice Over IP software (Internet Phone). Like many other VOIP products, it enables a computer user with internet access to have superb high quality voice conversations with friends and relatives from all over the world.