[esbeeb]

I run Prosody XMPP server on a cheap VPS, and appreciate how it's a stock Debian package, greatly simplifying security updates. It's delightfully lightweight on the server.

I use Conversations as a client in Android, and Gajim in Linux.

The basics like OMEMO, file attachments, push-to-talk voice memos (in Conversations, but not Gajim) work well. All comms are at least client-to-server-encrypted, and the OMEMO-protected comms are end-to-end encrypted.

[esbeeb]

actually, push-to-talk voice memos do work Gajim. An underrated feature!

Prosody allows voice and video calls - I have a TURN server all set up with it - but QOS rules (which are beyond my control, and are the fault of the ISPs I use) can sometimes squash calls made.

Gajim 1.9.3 (Flatpak) seems support voice and video calls to Conversations, but then it doesn't work. One Conversations smartphone can make voice and video calls to another Conversations smartphone.