A. The DN configuration for this phone is shared with SCCP phone, which is not supported.

B. The DHCP settings are incorrectly and the phone does not have an alternate TFTP defined.

C. The phone cannot download and install the latest firmware.

D. Auto-registration is disabled on the Cisco Unified Communications Manager nodes and the phone device does not have a DN configured.

E. The DN assigned to the phone is already in use by another SIP phone.