Matrix/Element has video rooms as a Lab function and for a while it had voice rooms too. Not sure what happened to them, but either way with MatrixRTC coming out the technical underpinnings are all there, clients just need to put it all together.

Someone mentioned (I believe?) after talking to Element/Matrix at FOSSDEM this year that the organization has been struggling a lot to get this going. Apparently issues with thier project organization forking and funding the last few years has made one of thier primary contributors, who already had fully functional and working video/voice, all but give up on the project because the upstream forming means it's now forked from a commercial/defunct version of the original code(?)