Question: Where can the current location estimate, known as the 'last known location', be stored according to 3GPP specifications, depending on national regulations?
Option 1: Only in the Home Location Register (HLR)
Option 2: Exclusively in the Serving GPRS Support Node (SGSN) for all networks
Option 3: In MSC/VLR, MSC Server, SGSN, or in H-GMLC as per regulatory requirements
Option 4: Solely in the User Equipment (UE) for privacy
Explanation: This option is correct because, according to the specifications, the storage of the 'last known location' can vary based on national regulations, and it may be stored in various network elements such as MSC/VLR, MSC Server, SGSN, or H-GMLC. This flexibility accommodates different legal and technical requirements across regions.