Correct Answer : Permanent Identity
Explanation : In telecommunication systems, network operator allocate to each SIM card a unique identifier, known up to the 4G as an IMSI (International Mobile Subscriber Identity) and for the 5G as a SUPI (Subscription Permanent Identifier). As authentication between a user and its network provider is based on a shared symmetric key, it can only take place after user identification. However, if the IMSI/SUPI values are sent in plaintext over the radio access link, then users can be identified, located and tracked using these permanent identifiers.
