I have been offered an IBM/ROLM phone mail system.
I'm curious if
it's something standard that's been put into use as a phone mail
system, or if it's some weird proprietary thing.
AFAIK, *ALL* phone switches are weird proprietary things. Some of the
latest small ones happen to be based on PCs, but their still weird
proprietary things.
The ROLM ones definitely are NOT PC-based, though, if that's what
you're asking.