Question: What is the primary purpose of verifying the freshness of the Sequence Number (SQN) by the User Services Identity Module (USIM) in a 3GPP network?
Option 1: To authenticate the network to the user, ensuring the network's legitimacy.
Option 2: To encrypt data transmissions between the User Equipment (UE) and the base station.
Option 3: To manage mobility and track the location of the UE within the network.
Option 4: To authorize access to specific services based on subscriber profiles.
Explanation: Verifying the freshness of the SQN by the USIM is crucial for entity authentication, specifically to authenticate the network to the user. This process ensures that the network the UE is communicating with is legitimate and not an impersonator, thereby protecting against certain types of attacks. This highlights the importance of sequence number management in maintaining security within telecom networks. (SQN: Sequence Number; USIM: User Services Identity Module)