Question

A network engineer registers a new Cisco 8865 SIP phone to CUCM. The phone obtains an IP address, downloads its configuration file from TFTP, and displays 'Registering.' However, it never completes registration. Packet captures show the phone sending SIP REGISTER messages on TCP port 5061, but CUCM never responds. The phone was configured with the default device security profile 'Cisco 8865 - Standard SIP Non-Secure Profile.' What is the most likely cause?

Accepted Answer

The device security profile specifies a non-secure transport (TCP/UDP 5060), but the phone is attempting TLS registration on port 5061

Answer

The phone firmware does not support SIP and must be downgraded to SCCP

Answer

The CUCM CallManager service is stopped on the publisher only

Answer

The phone's directory number has not yet been associated with an end user