1)   Cyber-What!? 1.0
Cyber-What!? is simple and powerful voice conferencing client/cerver solution for Windows. Supports up to 60 simultaneous speakers on your LAN or via Internet. 1.4kbps up to 350kbps transfer rates for maximum flexibility and resource utililization.

 2)   TeamTalk 3.0
TeamTalk is an internet based voice conferencing application that allows you to talk with your friends and colleagues using the internet as audio carrier.