Section: 4.13.3.2 Deregistration procedures for SMS over NAS
Content: If UE indicates to AMF that it no longer wants to send and receive SMS over NAS (e.g. not including "SMS supported" indication in subsequent Registration Request message) or AMF considers that UE is deregistered on specific Access Type(s) or AMF receives Deregistration Notification from UDM for specific Access Type(s) indicating UE Initial Registration, Subscription Withdrawn or 5GS to EPS Mobility as specified in clause 5.2.3.2.2, then: - AMF may, if the UE is not registered at other Access Type at the AMF any more, unsubscribe from SMS Subscription data changes notification with the UDM by means of the Nudm_SDM_Unsubscribe service operation. - AMF invokes Nsmsf_SMService_Deactivate service operation to trigger the release of UE Context for SMS on SMSF for the impacted Access Type(s) based on local configurations. - AMF may, if the UE is not registered at other Access Type at the AMF anymore, delete or deactivate the stored SMSF address in its UE Context. - The SMSF unsubscribes from SMS Management Subscription data changes notification with the UDM by means of the Nudm_SDM_Unsubscribe service operation if the UE is not registered at other Access Type for SMS over NAS service at the SMSF anymore. - The SMSF shall invoke Nudm_UECM_Deregistration (SUPI, NF ID, Access Type) service operation from UDM to trigger UDM to delete SMSF address of the UE for the impacted Access Type(s). The SMSF also removes the UE Context for SMS for the impacted Access Type(s), including AMF address. - The UDM may update UE context in SMSF in UDR by Nudr_DM_Update (SUPI, Subscription Data, SMS Subscription data, SMSF address). The UDM may remove the corresponding subscription of data change notification in UDR by Nudr_DM_Unsubscribe service operation.