Question: Where is the UE Reachability Request Parameter for the SGSN (URRP-SGSN) temporarily stored, according to 3GPP specifications?
Option 1: Only in the Home Location Register (HLR)
Option 2: Exclusively in the Serving GPRS Support Node (SGSN)
Option 3: Conditionally in both the Serving GPRS Support Node (SGSN) and the Home Subscriber Server (HSS)
Option 4: Solely in the Gateway Mobile Switching Center (GMSC)
Explanation: The correct storage locations for URRP-SGSN, as per the specifications, are both the SGSN and the HSS. This dual storage is conditional, indicating it's not always stored but rather under specific circumstances when UE activity notification from SGSN has been requested by the HSS. This setup facilitates efficient management of subscriber data in telecom networks, particularly for handling reachability requests and notifications.