Question: Where is the Default Public User Identity indicator, which marks the default Public User Identity for each Implicitly Registered Public User Identity Set, conditionally stored?
Option 1: In the UE (User Equipment) for quick access
Option 2: Across all eNodeBs for seamless handovers
Option 3: Within the MME (Mobility Management Entity) for session management
Option 4: In the HSS (Home Subscriber Server) as part of permanent subscriber data
Explanation: The Default Public User Identity indicator is a piece of permanent subscriber data, which implies it is stored in a centralized database that manages long-term subscriber information. Among the options provided, only the HSS (Home Subscriber Server) fits this description, as it is responsible for storing and managing subscriber data, including permanent data like the Default Public User Identity indicator. This storage location ensures consistent access to default identity settings across the network.