Question

A newly deployed Cisco IP Phone 8865 running SIP firmware fails to register with CUCM. Packet captures show the phone downloads its configuration file via TFTP successfully, but it never sends a SIP REGISTER message to the primary CUCM node listed in the config. The phone displays 'Registering' and then reverts to the same node repeatedly. The device is defined in CUCM and associated with the correct device pool. What is the MOST likely cause?

Accepted Answer

The phone's associated SIP profile has an unreachable outbound proxy configured, so the phone attempts to register through the proxy instead of the CUCM node.

Answer

The Device Pool's Cisco Unified CM Group has no secondary node, preventing failover registration.

Answer

The phone's directory number partition does not match the Calling Search Space assigned to the device.

Answer

The firmware load specified in the Phone Load Name field is missing from the TFTP server.