In rare cases a PBX had to be reset to get functional again. Symptoms were extensions or trunks that could not register and also music on hold not played any more. If you ever experience such a case a reset can be done by clicking Submit & Start in Personal Data.
Thanks for that. I've been struggling to get a line for over an hour. The problem was that the status showed all trunks as registered (green) but no dial tone.
I think this should be made a sticky to remind us if it happens again.