Question: What action is taken when the deregistration inactivity timer expires for an on-demand S-NSSAI?
Option 1: The UE sends a request to register with the Network Slice again.
Option 2: The AMF updates the Allowed NSSAI to include a new slice.
Option 3: The AMF and UE may locally remove the S-NSSAI from the Allowed NSSAI, or the AMF may send a UE Configuration Update Command to remove the slice.
Option 4: The UE establishes a new PDU session with the same S-NSSAI.
Explanation: When the deregistration inactivity timer expires for an on-demand S-NSSAI, the AMF and UE may locally remove the S-NSSAI from the Allowed NSSAI. This ensures that the UE is no longer registered with the Network Slice when it is not in use. Additionally, the AMF may send a UE Configuration Update Command to remove the slice from the Allowed NSSAI.