Mumble is fantastic for voice chat. Its text features are very basic, though, so people fleeing Discord would probably want something additional to handle that. Maybe Matrix.
A single location is a good selling point. Being able to jump into a voice chat, and still post things in a shared text chat is a good feature. Mumble should work a bit on that.
ecshafer|12 days ago
foresto|12 days ago
Mumble is a labor of love, not a commercial product. I expect they would appreciate your help.