Today’s phone is a bit of an anomaly in the USA. It’s a Norstar phone developed to work on the European and Australian markets under the branding “Commander.” The phone system was sold by the local telco (such as BT Commander in the UK) under this Commander name.
This M7310N is the exact same set as M7310, but in a sleek more modern housing. The housing looks closer to a Meridian1 telephone. In fact it matches the Euro Version of the Meridian 1 sets named the M3820 set.
For Norstar in Europe there are the M7100N, M7208N, M7310N, and M7324N sets.
In Europe for Meridian 1 there are the M3110 (M2008 Basic), M3310 (M2008HF) and M3820 (M2616) sets.
Finally the European Meridian Digital Centrex sets are called the M6310 (M5008) and M6320 (M5316) and ironically are now badged as Mitel phones. In 2000, Nortel sold the manufacture of Centrex and Small Business sets to Aastra which Mitel, one of Nortels big competitors, bought a few months ago and the sets are now owned by Mitel.