[Conditional] AMF to SMF: Nsmf_PDUSession_UpdateSMContext ().
For an Emergency Registered UE, this step is applied when the Registration Type is Mobility Registration Update.
The AMF invokes the Nsmf_PDUSession_UpdateSMContext (see clause 220.127.116.11.6) in the following scenario(s):
If the "PDU Session(s) to be re-activated" is included in the Registration Request in step 1, the AMF sends Nsmf_PDUSession_UpdateSMContext Request to SMF(s) associated with the PDU Session(s) to activate User Plane connections of the PDU Session(s). From step 5 onwards described in clause 18.104.22.168 are executed to complete the User Plane connection activation without sending MM NAS Service Accept from the AMF to (R)AN described in step 12 of clause 22.214.171.124.
The SMF may decide to trigger e.g. the intermediate UPF insertion, removal or change of PSA as described in step 5 in clause 126.96.36.199. In the case that the intermediate UPF insertion, removal, or relocation is performed for the PDU Session(s) not included in "PDU Session(s) to be re-activated", the procedure is performed without N11 and N2 interactions to update the N3 user plane between (R)AN and 5GC.
The AMF invokes the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF in the following scenario:
If any PDU Session status indicates that it is released at the UE, the AMF invokes the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF in order to release any network resources related to the PDU Session.
If the Registration type indicated by the UE is Periodic Registration Update, then steps 20 may be omitted.
If the serving AMF is changed, the new AMF shall wait until step 17 is finished with all the SMFs associated with the UE. Otherwise, steps 18 to 22 can continue in parallel to this step.
The mobility related event notifications towards the NF consumers are triggered at the end of this procedure for cases as described in clause 4.15.4.