I mentioned to the customer I didn't think it was the phone, he got it today (no wonder why Amazon is doing so well!) and the results were as expected. I emailed the customer a photo of an 18D and where the transfer key is. Hopefully he can try to see if the tech password is known. His main issue was accessing the Auto Attendant menu, which at the moment he can't. I have no idea what keys were what .I can only guess one was VMADM, voice mail administration.

Seems the system isn't that old (compared to some I work on)... the documentation I've found was from 2005. Thanks for the help so far.