1)   sharpVoice(tm) Client 6.0
sharpVoice is a internet telephony program that enables free PC-to-PC and inexpensive PC-to-Telephone voice conference calls even with slow internet connections.

 2)   BeyondPhone 2.4.1.0
BeyondPhone is future of internet telephony. You can make substantial savings on every outgoing call. Call anywhere in the world from your computer. For high call clarity and low calling rates , for details visit our website http://beyondphone.com

 3)   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.