e. 60. The PCF acknowledges the notification. 61. The PCF sends a Data Repository Update to the UDR with the UE policy data. 62. The UDR acknowledges this. This marks the end of the UE registration procedure. Here, we have seen that UE is authenticated and authorized, the security procedures are completed, and the various UE policies for access and mobility are obtained. The UE is now ready for the next step, which is to establish a PDU session. Phase 2 - PDU session establishment Following the PDU session establishment procedure, the UE can access the network. A PDU Session establishment can be of the following types: When a UE initiates a PDU Session Establishment Procedure When a UE initiates a PDU Session handover between 3GPP and non-3GPP networks When a UE initiates PDU Session handover from EPS to 5GS Once the PDU session has been established, the UE can access the data network (or VoNR network as applicable). Let us go over the various steps in a 5G PDU session establishment procedure. This procedure assumes that the UE has already registered with the AMF: 5G SA network design fundamentals (R)AN 1. PDU Session Establishment Request 2. SMF selection 3. Nsmf_PDUSession_CreateSMContext Request 4a-4b Registration/Subcription retrieval/ Subscription for updates 5. Nsmf_PDUSession_CreateSMContext Response 6. PDU Session authentication/authorization 7a. PCF selection 7b. SM Policy Association Establishment or SMF initiated SM Policy Association Modification 8. UPF selection 9. SMF initiated SM Policy Association Modification 10a. N4 Session Establishment/Modification Request 10b. N4 Session Establishment/Modification Responce 11. Namf_Communication_NIN2MessageTransfer 12. N2 PDU Session Request (NAS msg) 13. AN-specific resource setup (PDU Session Establisment Accept) 14. N2 PDU Session Request Ack First Uplink Data 15. Nsmf_PDUSession_UpdateSMContext Request 16a. N4 Session Modification Request First Downlink Data 16b. N4 Session Modification Response 17. Nsmf_PDUSession_UpdateSMContext Response 18. :Nsmf_PDUSe