Is the phone programmed to receive and place calls in the Handsets menu of the Allworx? On the "generic SIP phone" template that I have for our Aastra MBU400, you can't put call appearances on it, but you can make it ring on all lines and you can make it have dial "9" access.

Are you getting any support from your Vendor?? From Allworx??

Have you checked the call routes for the extensions menu?