The Nortel Meridian is a medium range PBX designed and sold as a follow-on to the successful line of SL-1 PBXes that came before it. Ranging from the small option 11 systems serving a couple hundred lines to the very large fiber network option 81 systems that could serve over thirty thousand lines, the Meridian line had wide applications.
In late 2020, I picked up a two-cabinet option 11c system locally for a pretty good price. The option 11c is a nonblocking design that can build out to 5 cabinets, supporting 50 IPE cards, and up to 800 lines (although this would leave no room for trunks). Digital trunk cards (e.g T1/E1) and certain other common equipment are only supported in the first cabinet slots 1-9, limiting the system to 9 of those cards.
These days, my Meridian is generally on all the time with a number of phones around the house attached to it.