They spend all of the $ on the Avaya and are constantly looking for a way to get rid of Nortel.
Several of the ex directors left service and are now working for the vendor of the Avaya equipment and I expect the pattern to continue" -- Aren't there some sort of conflict of interest laws at play here?
"The most damming arguement against upgrading the Nortel past Succession 3.0 is that it doesn't break, so why spend money?" -- this is an argument AGAINST Nortel?!?
Sounds like a no-win situation, but if the argument against Nortel is that it's so reliable that they don't need to spend any money on it, then maybe you could look at it from the budgetary standpoint of SAVING money by adding Nortel systems due to simplicity, reliability, and oh...I dunno...features. Nortel's site has plenty of competitive analyses between their systems and those of other manufacturers. Maybe you should download them and see if you can put together a case. Frivolity like SNMP to the set seems like tech for tech's sake and if "the other side of the house" has that much time on their hands, perhaps they have too many people for the current workload.