AMF-initiated PDU Session Release with N11 Release=True
The AMF-initiated PDU session release procedure allows the AMF to initiate the release of a PDU session with the N11 release in the SmContextModifyRequest being set to True.
The following figure depicts the AMF-initiated PDU session release call flow with the N11 release=True.

Step | Description |
---|---|
1 |
The AMF sends SmContextModifyRequest with release=True in 2 causes REL_DUE_TO_DUPLICATE_SESSION_ID or REL_DUE_TO_SLICE_NOT_AVAILABLE. |
2, 3 |
The SMF sends N4SessionReleaseRequest to the UPF. The UPF sends response for the same. |
4 |
The SMF sends SmContextUpdateResponse message with N1 and N2 content.
|
5, 6 |
The AMF exchanges message with RAN. The RAN forwards it to the UE. |
7, 8, 9 |
The RAN sends N2 release response to the AMF. The AMF sends N2 release response (N2_PDU_SESSION_RESOURCE_RELEASE_RESPONSE_TRANSFER) in N11 SmContextUpdateRequest message. The SMF responds back to the AMF as SmContextUpdateResponse. |
10, 11, 12, 13 |
The UE sends N1 release response in NAS message to the AMF through the RAN. The AMF sends N1 release response (PDU_SESSION_RELEASE_COMPLETE) in N11 SmContextUpdateRequest message. The SMF responds back to the AMF as SmContextUpdateResponse. |
14, 15 |
The SMF sends delete charging request to the CHF. The CHF responds back to the SMF with delete response. |
16, 17 |
The SMF sends SmContextStausNotify to the AMF. The AMF responds back with SmContextStausNotifyResponse message. |
18, 19 |
The SMF sends delete request to the PCF. The PCF responds back to the SMF with delete response. |
20, 21 |
The SMF sends UDM deregistration request. The UDM responds back to the SMF with deregistration response. |