Question: In the context of Completion of Calls to Busy Subscriber (CCBS) service, what is the source of the service state information stored in the Visitor Location Register (VLR) for both originating and destination networks?
Option 1: The service state information is generated locally within the VLR based on network traffic.
Option 2: The service state information is received from the Serving General Packet Radio Service (GPRS) Support Node (SGSN).
Option 3: The service state information is retrieved from the Mobile Switching Center (MSC).
Option 4: The service state information is received from the Home Location Register (HLR).
Explanation: In the CCBS service, accurate handling of call completions to busy subscribers requires up-to-date service state information. This information is centrally managed by the Home Location Register (HLR), which updates the Visitor Location Registers (VLRs) in both the originating and destination networks. This ensures consistency and reliability in service provisioning across different network elements, highlighting the HLR's role as a master repository for subscriber and service data.