The Cisco Unified IP Phone 9971 supports which protocol accessing the CLI to gather information and use debug commands?

SSHv2 is not supported on the Cisco Unified IP Phone 9971 for CLI access; Telnet is the designated protocol for remote command-line connectivity on this model.

SSHv1 is not a supported CLI access protocol on the 9971 phone, and it is also deprecated industry-wide due to known cryptographic vulnerabilities.

CDP (Cisco Discovery Protocol) is a Layer 2 neighbor discovery protocol used to exchange device and topology information between Cisco devices, not a mechanism for CLI access or debugging.

The Cisco Unified IP Phone 9971 supports Telnet as the only remote CLI access protocol, allowing administrators to connect to the phone's command-line interface to execute debug commands and retrieve diagnostic information. SSH is not supported on the 9971 for CLI connectivity, making Telnet the sole available option for remote command-line access on this phone model.