I'm not sure this is the right forum for this question -- although I'm confident I'll be told if not! -- but I've read the fine manual (at least, such a manual as I have), I've googled and I cannot get any insight into where to even start solving this problem.

I have a bunch of Mitel 5312 handsets, talking to a 3300 ICP controller. Some handsets are at a remote location, get an address from my DHCP server over there, and use the Mitel "Teleworker" extension to connect in over the Internet. The remaining handsets were set up with static IPs by a BT-supplied engineer, on the same subnet as the ICP itself. So far, so good.

I have one remaining teleworker licence, and need to move a handset from the home location to the remote. I've managed to boot it and configure teleworker, but I cannot for the life of me see where I tell it to forget its static IP, and make a DHCP request.

Any ideas? Should I be looking on the controller, or holding magic combinations of buttons on the handset itself?

EDIT: Following some advice from Robert, below, I've broken out a spare device and reassigned the profile for this user's extension to the MAC of the new phone, and a new profile to the old MAC. Unfortunately this still doesn't get me anywhere -- the new handset now asks for the teleworker install password.

I suspect I'm going to have to get a Mitel engineer involved here, since I've never been given that password... Unless anyone has any great ideas?