Oh, and the reason why the M5000 "P" phones are so popular? In the late 1980s, they were developed as digital replacements for 1A2 systems. Of course you could have multiple lines running to a desk with "one" line cord instead of an ampehnol connector....and unlike most 1980s PBXs with switch distance limitations, they could be placed in relatively remote locations miles away from the switch. I believe Avaya had their own version of Hosted Centrex phones. What were they? They worked on the ESS version of Centrex. Anyone remember?
Joseph Sus Jr. Nortel Enthusiast