Question: When transmitting CC (Content of Communication) over a physically separate DF (Delivery Function) from 3G INEs (Interception Network Elements), which security mechanism(s) MAY be optionally required for the X3-interface, as per national regulations?
Option 1: Only Encryption
Option 2: CUG/VPN, COLP, CLIP, Authentication, and/or Encryption
Option 3: Mandatory use of both Authentication and Encryption
Option 4: None, as security is not a concern for CC transmission
Explanation: According to specifications for secure CC transmission, especially when DFs are physically separate from 3G INEs or other interception nodes, national options may require the X3-interface to support various security mechanisms. These can include Closed User Group/Virtual Private Network (CUG/VPN) for secure network access, Calling Line Identification Presentation (CLIP) and Connected Line Identification Presentation (COLP) for caller/called party identification, Authentication for verifying identities, and Encryption for protecting data integrity and confidentiality. Thus, the correct answer encompasses all these potential security measures as optional requirements based on national regulations.