Are there free video conferencing software?

Question

open source

Hello everybody.
Please advise a free (if it exists) solution for video conferences for at least 20 people. If there are no free ones, I'll listen to the least expensive ones.
The functionality that interests you is holding conference calls in the form of "one speaks - everyone listens", but moreover, you can give the floor to one of the listeners.

Answer 1

Hangouts not an option?
I won’t even talk about Skype ... oh, I already said it.
Game services:
TeamSpeak
RaidCall
Discord - many have switched to it from Teamspeak and Skype.

Answer 2

teamviewer
or
google hangouts

Answer 3

Try OpenMeetings
https://openmeetings.apache.org/index.html

Answer 4

openmcu.ru

Answer 5

bigbluebutton