Where can I find the intallation & operation manual for a Nortel flash
voice mail "NT8B72AJ-93". I would pay for a download version.

http://www.twacomm.com/Catalog/Model_03420042.htm?SID=JM22KHGQU3079MUKHNGNPN2A0RVE082C
Might be of interest to you. You might call the 877 number during
normal business hours to be sure it's right.
03420042 is the model number for the book (startalk flash)

I am not a Google Answers Researcher.

I called TWAcomm.com They don't know if this manual is the right one
for my system... I have a "Norstar Startalk A" and the manual seams to
be for a "Startalk Flash" It might be the same but they don't
garranty...

Then you might want the
http://www.twacomm.com/Catalog/Model_3420003.htm?SID=JM22KHGQU3079MUKHNGNPN2A0RVE082C
because of its specification of 
 Installation & programming manual for the Nortel Startalk voicemail
system. Version 2.0.1 w/A/B/C Cabinets.

I only suggested the other because you said "Flash" in your question.
However, I don't have any idea where to go, especially since the
references are miniscule and 3 years old for the model you specified.