Question: How does a UE determine whether the Paging Cause Indication for Voice Service feature is supported in the current Registration Area by 5GC?
Option 1: Based on the information received from the NG-RAN in the RAN Paging message.
Option 2: By checking if it is supported by both the RAN, as indicated in the received Uu Paging message, and by 5GC, as indicated in the MUSIM capability exchange with the AMF.
Option 3: Based on the Voice Service Indication in the NGAP Paging Message from AMF.
Option 4: By detecting the downlink data which triggers the RAN Paging message is related to voice service based on the Paging Policy Indicator.
Explanation: The UE determines whether the Paging Cause Indication for Voice Service feature is supported in the current Registration Area by 5GC based on the MUSIM capability exchange with the AMF and the indication from the RAN, as specified in clause 5.38.1. This ensures that both the RAN and 5GC support the feature before the UE uses it.