VoRS -- Vo(IP) Really Simple.
Very simple and usable multi-user VoIP solution.
Some kind of alternative to Mumble without gaming-related features.
=> Mumble

But why? SIP-based solutions are pretty complicated to setup, because
they are not made for simple tasks like sudden voice chats between a
few people. WebRTC-based solutions are insane bloated incredible
monsters by complexity and size, hardly possible to debug and having
frequent compatibility problems. They work mainly only if you use the
same kind of software and codecs, for example Chromium, that requires
dozens of gigabytes of disk space and much RAM, CPU time to build it.
Taking an enormous amount of CPU power to slowly work with it. Is not
it pure insanity for such relatively simple task?

Mumble has wonderful simplicity and workability, but its client is
written on Qt, which requires hundreds of megabytes of additional
libraries to build it up. And users tend to complain about its newer
client versions quality and convenience.

So let's write as simple VoIP talking client as it is possible, without
compromising convenience and simplicity for the user! I just want a
simple command, which only requires to specify the server's address with
the key to just immediately talk with someone.

* No GUI requirement. Why would someone need a GUI for voice
  application? But a fancy real-time refreshing TUI would be desirable.
  Mumble tends to output no information, sometimes hiding the fact of a
  problem and that everything stopped working.
* Mono-cypher, mono-codec protocol.
* Maximal easiness of usage: here is your address, key, do me good.

VoRS is copylefted free software licenced under GNU Affero GPLv3.
It should work on all POSIX-compatible systems.

=> Copyleft
=> Free software
=> GNU Affero GPLv3
=> POSIX

Server (above) and two clients (left and right) in a terminal multiplexer:
Server and two clients

[Features]
[INSTALL]
[Usage]
[VAD]
[Protocol]