I had this issue preventing me to start a call, which happened on two different browsers. It turned out that the
pulseaudio service was hung, and no audio devices were available for the browser to use.
In that case it makes sense to check:
- if pulseaudio is running
systemctl status --user pulseaudio
- if pulseaudio is running, that you have a list from input (sources) and output (sinks) audio devices in the Gnome Desktop Settings. You can also check from the command line with
pactl list sources pactl list sinks