My friend Joseph sent me this pic of a Meridian Digital Centrex telephone from a medical center in Philadelphia.
This MDC M5316 telephones time and date is obviously not synced with the Nortel Central Office switch as this photo was taken in mid afternoon.
These telephones were originally called P telephones in Nortel lingo and they work directly off digital line cards on a Nortel DMS100 or SL100. Customers of this large carrier switch had the option to use the Meridian 1 Option Succession cabinets to control M2000 series digital telephones for multi line capability or they could run these M5000 sets directly off the switch for more primitive multi line call control . The only problem with the M5000 sets compared to that of the M2000 Meridian1 sets, was that the pure Centrex M5000 sets have basic features similar to an analog telephone and they require a large power brick to control each telephone.
The M5000 sets were completely redesigned in 1995 to look exactly like the M2000 Aries sets.
Contrary to what you might hear, these phones are still fully manufactured by Aastra Mitel and supported by Genband on their C20 Nortel CS2100 evolution switch. The only reason organizations such as my alma mater university in West Lafayette are pitching them, is companies like Cisco are coming in and saying to replace everything with Cisco and we will give you the telephones. Unfortunately they charge ridiculous amounts for support and licensing. It’s also a waste for landfills to throw away a perfectly good SL100/CS2100 Genband C20 switch that is still fully supported to just go with Cisco because everyone else is.
It’s like those Canadian Goose Down coats popping up everywhere on all the northern yuppies this winter. Sure you could keep your wonderful North Face or LLBean down coat that works perfectly fine, but since everyone else is buying the expensive $950 Canada Goose Down coats you might as well too. Hence pitching digital centrex and going to Cisco.