I want to selfhost a messaging service for my family. It should be secure and have voice calling option, ideally. Thank you.
Why? Existing platforms, especially the plain cell network, are going to be far more compatible and reliable.
Since we use Nextcloud, we just use Talk. It works well enough for us, but you should also host a TURN/STUN Server with that.
Also a vote for Matrix and Synapse. Works great and you can decide if you federate or not.
Mattermost is really nice. They added voice calling as a beta feature a while ago and it works pretty good so far.