210-060 · Question #57
Which Cisco Unified Communications Manager configuration causes an IP phone screen to display a "registration rejected" message?
The correct answer is D. Cisco Unified Communications Manager is unable to allocate DN. When Cisco Unified Communications Manager cannot allocate a Directory Number to a registering IP phone - typically because the auto-registration DN pool is exhausted - it sends back an explicit rejection that the phone displays as 'Registration Rejected'.
Question
Which Cisco Unified Communications Manager configuration causes an IP phone screen to display a "registration rejected" message?
Options
- ACisco Unified Communications Manager is unable to reach user IP phone.
- BCisco Unified Communications Manager database replication status is 2.
- CCisco Unified Communications Manager auto registration is disabled.
- DCisco Unified Communications Manager is unable to allocate DN.
- ECisco Unified Communications Manager subscriber is offline.
How the community answered
(29 responses)- A7% (2)
- B3% (1)
- C14% (4)
- D76% (22)
Why each option
When Cisco Unified Communications Manager cannot allocate a Directory Number to a registering IP phone - typically because the auto-registration DN pool is exhausted - it sends back an explicit rejection that the phone displays as 'Registration Rejected'.
If CUCM cannot reach the phone, the phone would display a timeout or 'Configuring IP' message, not a rejection from CUCM.
Database replication status 2 indicates successful replication and is a healthy state that does not cause phone registration to be rejected.
Disabling auto-registration prevents unknown devices from being automatically provisioned, but a pre-configured phone would still register; the behavior and message differ from a DN allocation failure.
CUCM assigns a DN from its auto-registration pool when a new phone attempts to register. If no DN is available or CUCM cannot complete the DN allocation, it responds with a RegistrationReject message per the SCCP/SIP registration flow, causing the phone screen to display 'Registration Rejected' rather than a generic connectivity error.
A subscriber node being offline would cause phones to fail over to another node or display a connection error, not a 'Registration Rejected' message.
Concept tested: CUCM IP phone registration and DN allocation failure
Source: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/12_5_1/adminGuide/cucm_b_administration-guide-1251/cucm_b_administration-guide-1251_chapter_0100.html
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