my thoughts exactly.. i never even asked when I ordered the phone. . just assumed it would work in a SIP mode.. it has the "phone mode" option and I changed it to SIP. . but then get that error.,.,, im running it on MCD 4.1, although I think there is a newer load or 2 for the mitel.. maybe ill upgrade my MXe to the latest.. just to see if they dropped a newer 5360 load in.... fortunately the phone was bought with marketing dollars and its all still in a LAB set up.
-Christopher