Jitsi
From Organic Design wiki
Jitsi is a fully open source and self-hostable video conferencing alternative to commercial products like Skype and Zoom. It is extremely easy to install taking literally five minutes. We've used this a lot now and have found this to be the only libre alternative for which the call quality to be as good or better than any of the commercial products we've tried.
Installation
The Quick installation guide automatically installs the system into an existing Nginx or Apache if one is found, so on a clean machine it's a good idea to install one first. It uses LetsEncrypt to create certs for SSL setup. Here's a list of the listening services that are running after the system is installed:
tcp 0 0.0.0.0:80 0.0.0.0:* LISTEN 505/nginx
tcp 0 0.0.0.0:5269 0.0.0.0:* LISTEN 450/lua5.2
tcp 0 0.0.0.0:8888 0.0.0.0:* LISTEN 399/java
tcp 0 0.0.0.0:4443 0.0.0.0:* LISTEN 454/java
tcp 0 0.0.0.0:443 0.0.0.0:* LISTEN 505/nginx
tcp 0 0.0.0.0:5280 0.0.0.0:* LISTEN 450/lua5.2
tcp 0 127.0.0.1:5347 0.0.0.0:* LISTEN 450/lua5.2
tcp 0 0.0.0.0:5222 0.0.0.0:* LISTEN 450/lua5.2
udp 0 0.0.0.0:55914 0.0.0.0:* 454/java
udp 0 0.0.0.0:58434 0.0.0.0:* 399/java
udp 0 0.0.0.0:10000 0.0.0.0:* 454/java
