[AusNOG] Recovering "disconnected" POTS number??

[Ross Wheeler]

Just had a call from an old ISP friend.
He has a quite upset customer of 20 odd years who has (reason not 
currently known) had their business telephone disconnected this morning.

I was not disconnected for non-payment, I get the impression it's 
something to do with nbn. The cause is largely unimportant...

They've been on to telstra to try to at least have the number diverted to 
a mobile - but the word just back is that because it's been "disconnected" 
they can't (won't?) do it.

I dare say we can't port it out either.

Nobody I've been able to talk to has had any idea how to recover the 
number. My guess is it is now in some embargo state before going "up for 
grabs". Problem is that it's a family business that's been going forever, 
the number is well known in their area - advertising, cards, white and 
yellow pages, peoples phones, etc.  They'd REALLY like to get it back.

I can't believe it isn't possible, so obviously it's a case of talking to 
the right people to make it happen. I don't know who "the right people" 
might be, or what magic incantations might need to be uttered. Are any of 
the good people here able to offer some meaningful advice?

TIA,
R.