Question: When a PCRF (Policy and Charging Rules Function) disables usage monitoring for a specific monitoring key, what action must the PCEF (Policy and Charging Enforcement Function) take regarding accumulated usage since the last report?
Option 1: The PCEF shall discard the accumulated usage to free up resources.
Option 2: The PCEF shall continue to accumulate usage without reporting until re-enabled.
Option 3: The PCEF shall send a new CCR with CC-Request Type set to "INITIAL_REQUEST" for the disabled key.
Option 4: The PCEF shall send a new CCR command with CC-Request Type AVP set to "UPDATE_REQUEST" and Event-Trigger AVP set to "USAGE_REPORT" to report accumulated usage.
Explanation: When the PCRF disables usage monitoring, it is crucial for the PCEF to report any accumulated usage that occurred while monitoring was enabled. This ensures accurate billing and resource management. By sending an UPDATE_REQUEST with a USAGE_REPORT event trigger, the PCEF provides the necessary update on the accumulated usage for the disabled monitoring key(s), aligning with efficient network operation and data integrity principles in telecom networks.