Question: Upon receiving a REGISTRATION ACCEPT or DL NAS TRANSPORT message with specific conditions, how should the Mobile Equipment (ME) handle the secured packet for SMS-PP data download if integrity check is successful?
Option 1: The ME shall display the message to the user and request confirmation before processing.
Option 2: The ME shall alert the user about the incoming data but not display the content, then process the packet internally.
Option 3: The ME shall reject the message if it's part of a concatenation of SMS-Deliver TPDUs to ensure security.
Option 4: The ME shall pass the message(s) transparently to the UICC using the ENVELOPE (SMS-PP DOWNLOAD) command without user notification.
Explanation: According to the specified procedure for SMS-PP data download, once the integrity check of the REGISTRATION ACCEPT or DL NAS TRANSPORT message is successful, the ME's role is to forward the secured packet to the UICC using the ENVELOPE (SMS-PP DOWNLOAD) command. This process occurs transparently, without notifying or involving the user directly, ensuring seamless and secure data download to the USIM application.