(R)AN to new AMF: N2 message (N2 parameters, Registration Request (as described in step 1) and UE Policy Container.
When NG-RAN is used, the N2 parameters include the Selected PLMN ID, Location Information and Cell Identity related to the cell in which the UE is camping, UE Context Request which indicates that a UE context including security information needs to be setup at the NG-RAN.
When NG-RAN is used, the N2 parameters also include the Establishment cause.
Mapping Of Requested NSSAI is provided only if available.
If the Registration type indicated by the UE is Periodic Registration Update, then steps 4 to 19 may be omitted.
When the Establishment cause is associated with priority services (e.g. MPS, MCS), the AMF includes a Message Priority header to indicate priority information. Other NFs relay the priority information by including the Message Priority header in service-based interfaces, as specified in TS 29.500 .