Question

A batch of new Cisco IP phones at a branch site fails to register with CUCM. The phones power up via PoE and show an IP address in the data VLAN subnet (10.10.20.0/24) instead of the voice VLAN subnet (10.10.30.0/24). Data PCs on the same switch ports work normally, and CUCM is reachable from the data VLAN. Which action most likely resolves the registration problem?

Accepted Answer

Configure the access switch ports with a voice VLAN (auxiliary VLAN) so phones receive the correct VLAN via CDP/LLDP-MED

Answer

Enable DHCP option 150 on the data VLAN scope to point phones to the TFTP server

Answer

Add the phones manually in CUCM using auto-registration on the CallManager service

Answer

Increase the PoE power budget on the switch to allow the phones to boot fully