|more useful options|
it appears Jitsi is a link embedder
It isn't clear at all how you came to that conclusion. Jitsi is a VoIP + IM solution.
If there are some FOSS options
There are loads of them. I would be using Asterisk for VoIP and probably Prosody for IM. If you are looking for a Perl answer then DJabberd is still available but (unfortunately) it has had no active development for a long time.
Update: although DJabberd hasn't seen a release in a decade there actually has been some more recent activity over on the github repo so it might not be quite such bad news on that front as it first appeared.
In reply to Re^3: Is a Perl Skype-like VoIP connection possible?