Question: In a 3GPP-compliant telecom network, what are the factors based on which the charging system can select the applicable rate for a user's service usage? (Select all that apply)
Option 1: User Equipment (UE) Type, Location (with specified granularity), and Time of Day
Option 2: Location (with specified granularity), User CSG Information (including CSG ID, access mode, and membership indication), and Radio Access Technology (RAT) type
Option 3: Service Type, User Subscription Status, and Network Congestion Level
Option 4: Device IP Address, Browser Type, and Download Speed
Explanation: According to telecom charging control principles, the correct answer reflects factors directly influencing charging rates in a network. Location (with specified granularity) affects billing due to varying regional tariffs. User CSG (Closed Subscriber Group) Information, including ID, access mode, and membership indication, can determine special rate plans or restrictions. RAT (Radio Access Technology) type, such as 4G, 5G, etc., influences charging based on the technology's bandwidth and service capabilities. These factors are crucial for dynamic, context-aware billing in modern telecom networks.