Cyber-What!?
Cyber-What!? is simple yet powerful voice conferencing Client/Server solution for Windows. Supports up to 60 simultaneous speakers on your LAN or via Internet; 1. 4kbps up to 350kbps transfer rates provide maximum flexibility and resource utilization - suitable for slow modem connections as well... Use configurable, global shorcut keys to instantly speak to groups of contacts, from any application, or simply select contacts and let VOX transfer your voice when it's detected! ... Centralized transfer rates and voice quality settings put your network administrator in charge of bandwidth...
http://www.cyberwhat.co.yu/download/CyberWhat.exe - 900Kb - Download - Screenshot