Skype conference calls could be about to get a whole lot busier. Microsoft is planning to bump up the maximum number of group call participants from 25 to 50 (18 more than can fit into a Group FaceTime call). The audio and video buttons will be enabled for larger groups, so people can more easily mute their microphones or turn on/off their webcam.
So you don't bother people who can't join a call too much, Skype also plans to make ringing optional. It will instead send a notification to group call participants, though you can still ask Skype to ring people if they don't respond. These features are available as of today for beta testers, and they'll likely roll out more broadly later.