I'm digging online live classroom sessions

It's part chat room, part conference call, and very classroom-like. We have a whiteboard to look at where someone posts notes. It's either the instructor or facilitator who does it. We can "raise our hands" to talk and actually hear each other's voices. But it's not a conference call. It's Internet telephony so we can be online having our classroom session for an hour and it doesn't hurt our phone bills. It's also nice to have a discussion with as many classmates together at once as possible.