I know this sounds silly but is there only one controller at site?
Check network settings of the phone and make sure that it is trying to connect where you think.
It is a hosted controller.
But there could indeed be a issue with the phones settings that i cant find the controller.
Maybe some wrong MAC address was recorded in the MBG server and therefore Plainside had to use replacement code instead.
we tested it with the replacement code also wouldn't work sadly.
Edit,
We probably found the problem.
Before shipping the phone out one of my colleagues made the phone factory default...
Thinking there was a DHCP in place on location, which there is not.
So I will have to walk them through the process of configuring the phone, over the phone.
But if it still doesn't work after that I wouldn't know what else could be wrong.