Question: In an EVENT DOWNLOAD – Incoming IMS Data scenario, as per USIM Application Toolkit (USAT) specifications, what is the expected setting for 'Device Identities' in the command parameters/data sent from the Mobile Equipment (ME) to the Universal Integrated Circuit Card (UICC)?
Option 1: Source: UICC; Destination: Network
Option 2: Source: Network; Destination: ME
Option 3: Source: Network; Destination: UICC
Option 4: Source: ME; Destination: Network
Explanation: In the context of Incoming IMS Data, device identities are set to indicate the origin and target of the event. Since the event is an incoming IMS message destined for the UICC, logically, the source should be the entity initiating the communication (Network), and the destination should be the intended recipient (UICC). This setting aligns with how such communications are typically routed and processed within a telecom network, emphasizing the direction of the incoming message.