Quoting karl@??? (karl@???):

> https://en.wikipedia.org/wiki/Comparison_of_web_conferencing_software
> lists four open source systems:
>
> https://en.wikipedia.org/wiki/Jitsi
> https://en.wikipedia.org/wiki/Jami_(software)
> https://en.wikipedia.org/wiki/OpenMeetings
> https://en.wikipedia.org/wiki/BigBlueButton

Thank you, sir.

> Anyone knows which one to choose for a smallish group (< 20 persons) ?

Logically, the only people truly qualified to answer your question
would be people who've setup/administered at least a large subset of the
above four, or who are in close contact with someone who has. I'm not
such a person; I've set up, administered, and used Jitsi Meet (only) --
and I've been a user of BigBlueButton instances used by Linux Users of
Victoria (Aus.) and by Arizona Ubuntu LoCo. It would be wonderful if a
qualified person is on this mailing list and can answer.

Until then, I can only say that Jitsi Meet struck me as quite practical
for a smallish group. The server software grabs gobs of RAM (judged by
my old-school sysadmin standards), but that outcome is to be expected
because it's Java.

FWIW, I note that Jami does voice (SIP) and instant messaging, but not
videoconferencing. The other three are generally similar WebRTC-based
systems.