Having resolved my issues with setting up a remote 53xx phone I now wish to get my test phone to work in the office again.
First I modified the phone's NAT address type back to Native and the Call Configuration back to local.
Then I plugged in the phone and took it out of Teleworker mode by selecting No.
Is there something more to do? The phone is not reconnecting to the office 5000 system.
Note: I have not left the system settings for use by a remote phone as I will have one in a day or so.