Question: What happens when the UE receives a REGISTRATION ACCEPT message without a specified value for timer T3502 and the 5GS registration type IE in the REGISTRATION REQUEST message is not set to "periodic registration updating"?
Option 1: The UE applies the last received value of timer T3502.
Option 2: The UE uses the default value of timer T3502.
Option 3: The UE sends a REGISTRATION REJECT message to the network.
Option 4: The UE initiates a new registration procedure.
Explanation: According to the specification, when the UE receives a REGISTRATION ACCEPT message without a specified value for timer T3502 and the 5GS registration type IE in the REGISTRATION REQUEST message is not set to "periodic registration updating", the default value of this timer is used. This ensures that the UE has a valid value for timer T3502, even if it was not explicitly provided by the network.