Question: What is the primary purpose of the network-initiated NAS transport procedure in a 5G System (5GS)?
Option 1: To provide a transport for only SMS messages.
Option 2: To establish an MA PDU session for LADN DNN.
Option 3: To forward uplink 5GSM messages that were not forwarded due to routing failure or congestion control.
Option 4: To provide a transport of various types of messages, including 5GSM messages, SMS, LPP messages, and more from the AMF to the UE in a 5GMM message.
Explanation: The network-initiated NAS transport procedure is designed to handle multiple types of messages, not just limited to one specific type. This includes various scenarios where uplink 5GSM messages were not forwarded due to different reasons such as routing failure, congestion control, or reaching the maximum number of PDU sessions. Therefore, option 4 accurately reflects the primary purpose of this procedure by encompassing all these possibilities.