I just found some time to continue this investigation, the good news is with the new Distro loaded Campon is functioning as I would expect it to.
A little refinement would be for the calling back message to say the extension number that is being caalled. Is this easy? If so will open a wish list ticket.
I’m using the distro (which works great by the way)
But as mentioned above the camp-on only functions when callwaiting is enabled. If it is disabled the line is busy, if you then dial *82 you will hear the beeb but nothing happens. The same with call waiting on you will be called when the other party hangs up.