Question: For 5G ProSe Unicast/Broadcast/Groupcast Direct Communication and Direct Communication via ProSe UE-to-Network Relay, what types of charging mechanisms can be utilized based on the configuration of related functions and the Charging Handling Function (CHF)?
Option 1: Only Session-Based Charging for all communication types
Option 2: Either Event-Based Charging or Session-Based Charging, depending on configuration
Option 3: Volume-Based Charging exclusively for Direct Communications
Option 4: Time-Based Charging solely for ProSe UE-to-Network Relay
Explanation: The correct answer is Option 2 because, according to the specifications for 5G ProSe Direct Communication charging, both Event-Based Charging and Session-Based Charging can be employed. The choice between these two mechanisms depends on how the ProSe related functions (e.g., 5G DDNMF in HPLMN) and the Charging Handling Function (CHF) are configured. This flexibility allows for tailored billing strategies based on the specific requirements of different direct communication services.