BigBlueButton
5.0 ex V stellae (secundum recensionem I)
BigBlueButton est fons apertus ratio conferendi interretialem ad discendi rationem destinata. BigBlueButton est instrumentum ab instructoribus adhibitum, quod adiuvat aditum ad Systema discendi, instrumenta pugnandi et analytica.
You can install BigBlueButton on your own server since it is open-source. There are definitely no ads, but they implemented this “Learning Analytics Dashboard” that is about analyzing the activity from the participants. That tool is used in schools and not for profit purposes I guess. Either way it is a trade-free video conferencing software.