Which action resolves this issue?

Company A merged with company B. An engineer is asked to register some IP phones from company B to Cisco Unified Communications Manager of company A. The engineer correctly added the devices in Cisco Unified CM and the network parameters for the IP phone are correct, but the IP phone is not registering.

Which action resolves this issue?

A. Enable SIP Proxy

B. Erase CTL configuration.

C. Change the device template

D. Configure H.323

Answer: D