Question: In the context of the 5G System (5GS), what unique identifier is allocated to each subscriber for use within the 3GPP system, as per system architecture specifications?
Option 1: Permanent Equipment Identifier (PEI) - Unique to each device
Option 2: International Mobile Subscriber Identity (IMSI) - A legacy identifier for GSM and UMTS
Option 3: Mobile Equipment Identifier (MEID) - Used for device identification in CDMA networks
Option 4: 5G Subscription Permanent Identifier (SUPI) - Allocated per subscriber for 5GS use
Explanation: The correct answer is Option 4 because, according to the system architecture for the 5G System, each subscriber is allocated one unique identifier for use within the 3GPP system, which is specifically termed as the 5G Subscription Permanent Identifier (SUPI). This distinguishes it from identifiers used for devices (like PEI) or those from legacy systems (like IMSI), highlighting SUPI's role in identifying subscribers uniquely within the 5GS.