Hi Keith,
The device is not supported, however it does not necessarily mean that it won't work.
Try to enter your extension credentials manually as well as the registrar and try to register them.
You can try it and see if it works ok. Make a few test calls, transfers, hold/unhold, mute/unmute, conference and if all works ok you should be able to use it. Make sure that you have 2 way audio in all scenarios where you would expect to hear audio.
Please note however that beyond basic functionality, the phone might misbehave compared to supported phones. In that case if you want to feel confident you wont face significant issues with your deployment, its' better to stick to supported models.
