Question: When an Application Function (AF) sends an HTTP POST message to create a resource for applying a Background Data Transfer (BDT) policy to a UE or group of UEs, how does the Network Exposure Function (NEF) proceed if the AF is authorized?
Option 1: The NEF directly applies the BDT policy without interacting with any other network function.
Option 2: The NEF interacts with the Unified Data Repository (UDR) to retrieve the SUPI or Internal Group Identifier.
Option 3: The NEF invokes the Nudm_SubscriberDataManagement service of the Unified Data Management (UDM) to retrieve the necessary identifiers.
Option 4: The NEF responds with a '401 Unauthorized' status code regardless of the AF's authorization.
Explanation: Upon receiving an authorized HTTP POST request for creating a BDT policy resource, the NEF must interact with the UDM to retrieve the SUPI or Internal Group Identifier. This step is crucial for identifying and applying the policy correctly to the UE(s) or group(s). Invoking the Nudm_SubscriberDataManagement service of the UDM is the specified procedure for this purpose.