Sys is a MICS 7.1/CP-100. I have programmed every phone with 2 I/C keys. F980 and F986 are programmed as feature keys.
FYI: If a station is doing a lot of call directing/answering, you may need more than two intercom keys. As Curlycord notes in the thread he linked to, the transfer-to-mailbox command requires an intercom path from the station to the voice mail unit (VMU). So if the station has one intercom call on hold, and gets a second call on the other intercom key, F986 won't work because there are no free intercom paths out. This isn't a problem if you've got all lines assigned to key appearances and you don't take a lot of intercom calls.
F980 works ok with adl keys.
It doesn't on any Norstar/BCM system I've worked with. Can you confirm this yourself, in person? (Don't take the user's word for it.) Also, check the programming on the keys with F*0; make sure they're programmed the way you think they are.
In my experience: When you press an autodial key, the system sees that as a request to dial that station. So it puts any active call on hold, looks for a free intercom path, and dials the station using that path. If you're talking to the VMU at that time, the voice mail system will either end up on-hold on another intercom key, or release you.
F986 will not transfer CO calls to user MBX with adl key.
Right. See above.
This works if the user pushes Fkey then manually (using the keypad) inputs MBX.
When you invoke F980 or F986, you're actually calling the VMU. If you look closely, you'll notice it consumes an intercom path. So the prompt you're seeing to enter a mailbox number is generated by the VMU. The way Nortel designed the system, pressing an autodial key at that point is seen as a request for a new call.
The customer said it worked with the system before CICS 7.0.
Customer is confused and/or lying.