Question: What represents the Subscriber Identifier (Subscriber ID) for a 3GPP User Equipment (UE: User Equipment) in mobile networks?
Option 1: IMSI (International Mobile Subscriber Identity)
Option 2: Access Line Identifier (physical and logical circuit ID)
Option 3: Username (e.g., used in PPP Sessions)
Option 4: MAC Address of the UE
Explanation: In mobile networks, specifically for 3GPP User Equipment (UE), the Subscriber Identifier is standardized as the IMSI. This unique identifier is crucial for authenticating and managing subscriber services within the network. Unlike fixed broadband access scenarios where identifiers like Access Line Identifiers or usernames might be used, the IMSI is the designated Subscriber ID for mobile UEs, ensuring seamless and secure service provision across different network infrastructures.