Question: In a Generic Bootstrapping Architecture (GBA) scenario, when a BSF requests authentication data using the Nhss_GbaUEAuthentication_Get service operation with only an MSISDN, what additional information must the HSS include in its response?
Option 1: IMSI and IMPI
Option 2: Only IMSI
Option 3: Only IMPI and Authentication Data (e.g., AV)
Option 4: No additional identities, only Result Indication
Explanation: According to the GBA specifications, if the request contains only an MSISDN, the HSS must return the corresponding IMSI in the response. Since the question specifies the request was made with an MSISDN, the HSS's response must include the IMSI. Authentication Data (e.g., AV) is optional and not mandated by this specific scenario's conditions.