Question: What happens to PDU Sessions associated with non-3GPP access when a UE undergoes inter-system handover from 5GS to EPS for PDU Sessions associated with 3GPP access?
Option 1: The PDU Sessions associated with non-3GPP access are automatically released.
Option 2: The network keeps the PDU Sessions associated with non-3GPP access anchored in 5GC, and the UE may choose to keep them in 5GS or release them locally or explicitly.
Option 3: The PDU Sessions associated with non-3GPP access are transferred to EPS without any action from the UE.
Option 4: The UE is disconnected from both 3GPP and non-3GPP accesses.
Explanation: According to the 3GPP TS 23.501 specification, when a UE undergoes inter-system handover from 5GS to EPS for PDU Sessions associated with 3GPP access, the network keeps the PDU Sessions associated with non-3GPP access anchored in 5GC. The UE then has the option to either keep these sessions in 5GS or release them locally or explicitly. This ensures that the UE can maintain connectivity over both 3GPP and non-3GPP accesses, even after the handover.