Fluxer: Free, open source instant messaging and VoIP platform (github.com)

> I know it's hard to resist, but please wait a little longer before you dive deep into the current codebase or try to set up self-hosting.

There are some decent FOSS VoIP platforms already. I'm just waiting for one that will register phone numbers like Google Voice does.

Discord lawyers are going to have a field day with that logo design and app look and feel.