Exploring alternatives, particularly open source, for conferancing
mumble is open source audio conferencing -
Big Blue Button
BigBlueButton is an open source web conferencing system built on over fourteen open source components to create an integrated solution that runs on mac, unix, or PC computers
Secure video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS, and IM network. All this, and more, in Jitsi - the most complete and advanced open source communicator.