Which Cisco Unified CM service is installed by default and authenticates certificates on behalf of IP phones and other endpoints?

Cisco CTL Provider is primarily responsible for updating the Certificate Trust List (CTL) file, which contains security parameters and certificates, to phones, rather than authenticating individual endpoint certificates dynamically.

Cisco Certificate Authority Proxy Function (CAPF) is used to enroll and provision device certificates to IP phones and other endpoints, acting as a proxy to an enterprise CA, but TVC performs the verification.

The Cisco Trust Verification service (TVC) is a crucial component installed by default on Cisco Unified CM. It authenticates and validates certificates for secure endpoints, including IP phones, ensuring that they can securely register and communicate with the CUCM.

Cisco CallManager service is the core call processing engine, responsible for call control, signaling, and resource management, but it relies on other services like TVC for certificate authentication.

Cisco TFTP (Trivial File Transfer Protocol) service provides configuration files, firmware, and other files to IP phones and devices, but not certificate authentication.