It's free. It has apps for iOS and Android and you can also phone in. I've never used it for such large meetings, but apparently it handles 100+ people fine [0]

It's free. It has apps for iOS and Android and you can also phone in. I've never used it for such large meetings, but apparently it handles 100+ people fine [0], and they have a blog post about scaling [1]. [0]: https://www.callstats.io/blog/2017/10/09/jitsi-atlassian-webrtc https://www.callstats.io/blog/2017/10/09/jitsi-atlassian-web... [1]: https://jitsi.org/jitsi-videobridge-performance-evaluation/ https://jitsi.org/jitsi-videobridge-performance-evaluation/