Question: In a Diameter charging application, when is the SM-Service-Type AVP required to be present in a charging interaction for SMS services?
Option 1: Always, for all types of SMS services
Option 2: Only for SMS services that involve Short Message forwarding
Option 3: When the SM-Message-Type AVP has a value indicating an SM Service Request (value 2)
Option 4: For vendor-specific SM services only (values 100-199)
Explanation: The correct answer is tied to the specific condition under which the SM-Service-Type AVP must be included in a charging interaction. This AVP is mandatory when the type of message being handled is an SM Service Request, denoted by the value 2 of the SM-Message-Type AVP, ensuring accurate identification and processing of the SMS service type involved.