I'm not really sure. I'm kind of a newbie when it comes to phones. I am the IT guy where I work, and this responsibility seemed logical to my boss, so guess who is the phone admin as well?
I just know it's a Nortel Norstar-Plus (ICS I think?) just because that is what is on the manuals I have. But I'm not even sure these are the latest and greatest manuals.
My Norstar Voicemail Manual is Version 2.1
My ICS is 1.1
Sorry for the lack of info...