Making a #sip call from the #calls app on the #librem5 (and yes audio worked ;) ). This is still a development version of gnome-calls. And work still needs to be done to make it more user friendly and integrated with other components. But hey it is progress :D
Credits go out to: @devrtz that has been working to add #sip on gnome-calls. Also the account on the phone is an jmp.chat account, shoutout to them as jmp.chat is an awesome service :D