Input user name in Jitsi or Jigasi

Attempting to coinnect to my voximplant number through Jigasi. Tech support at Voximplant reports that Jigasi or Jitsi has the incorrect user, “Jigasi-dial-in-user”. Where do I configure the user in Jigasi or Jitsi for Voximplant to connect?

Thank you.

This is the template https://github.com/jitsi/jigasi/blob/master/jigasi-home/sip-communicator.properties#L20
it is in /etc/jitsi/jigasi/sip-communicator.properties

Thank you. I have reinstalled Jigasi with correct user and password. I can dial into Voximplant but somehow Jitsi is still not capturing the call. I have called, entered meeting ID and password then the call just hangs.