Question: In a 5G-NR network, when sending a REGISTRATION REQUEST message after receiving a new SUCI (Subscription Concealed Identifier), what should the UE (User Equipment) use as the 5GS mobile identity IE instead of the 5G-GUTI or Last visited registered TAI?
Option 1: The previously stored 4G IMSI (International Mobile Subscriber Identity)
Option 2: A randomly generated temporary ID to enhance security
Option 3: The new SUCI received from the UICC (Universal Integrated Circuit Card) in response to a GET IDENTITY command with Identity Context set as SUCI (0x01)
Option 4: The UE's MAC (Media Access Control) address for simplicity
Explanation: After receiving a new SUCI from the UICC in response to a GET IDENTITY command with the Identity Context set as SUCI, the UE must use this new SUCI as the 5GS mobile identity IE in the REGISTRATION REQUEST message for secure and updated network registration, aligning with 5G-NR security protocols.