Actions performed by Cisco Unified IP Phone Trust List

DE.

The initial Trust List (ITL) is a security feature used by Cisco Unified IP phones to ensure the authenticity and integrity of the configuration files they receive from the Cisco Unified Communications Manager (CUCM). The ITL is a digitally signed list of all the CUCM servers that the phone trusts to receive and validate configuration files.

Here are the two actions that the Cisco Unified IP phone uses the ITL to perform:

1. Authenticate their configuration file signature: The phone uses the ITL to verify the digital signature of the configuration file it receives from the CUCM. If the signature is valid and matches the ITL, the phone will accept the configuration file and apply its settings. If the signature is not valid or does not match the ITL, the phone will reject the configuration file and display an error message.

2. Decrypt secure XML files: The phone uses the ITL to decrypt secure XML files that contain sensitive information, such as user credentials or device settings. These XML files are encrypted with a key that is stored on the CUCM server and distributed to the phone via the ITL. Once the phone receives the encrypted XML file, it uses the ITL to decrypt the file and access its contents.

Therefore, options A and D are the correct answers, as they correctly describe the actions performed by the Cisco Unified IP phone using the ITL. Option B is incorrect because the ITL does not encrypt RTP traffic; instead, it is used to authenticate configuration files. Option C is incorrect because the ITL is not used to download background image files. Option E is incorrect because CAPF (Certificate Authority Proxy Function) is a separate security feature used to support secure communications between the phone and the CUCM, but it is not directly related to the ITL.