 establishment procedure. IMS 5G PDU session establishment gNB/RAN PCSCF N4 SX Session Est Req N4 SX Session Est Response N4 SX Session Est Response Assign EBI Request Assign EBI Response N1N2 TransferRequest Assign EBI Response Figure 7.20 - IMS PDU attach procedure - part 3 Step 17: The SMF sends a PFCP session establishment/modification request to the UPF and provides packet detection, enforcement, and reporting rules to be installed on the UPF for this PDU session (PDR, QER, FAR, and URR). Step 18: The UPF responds with uplink tunnel information. Step 19: The SMF sends an HTTP GET request, http: //x.x.x.x:8080/nnrf-disc/vl nf - instances?requester-nf-type=SMF&target-nf-instance-id=bbe596c6 - - 0a81-4e94- - - 85bc -f3b1b4a9a52f&target-nf-typ - AMF/, for AMF instances, and the NRF responds with 200 OK with the service instance ID, API versions, NF service status, and IPv4 addresses. Step 20: In the sm create context request, AMF sends epsinterworkingind" : "WITH N26, and seeing this indicator, the SMF sends an AssignEBI HTTP POST request to the AMF (http: x.x.x.x: 8080/na 1mf-comm/v1/ue-contexts/imsi-123xxxxxxx/assigebi/) - with the ARP list and PDU session ID. Step 21: The AMF responds with assignedEbiList (ARP, value, and EPS bearer ID). Packet Core Procedures Step 22: The SMF sends an HTTP POST request to AMF (http://x.x.x.x : 8080/namf - comm/ v1/ue-contexts/imsessages/N1N2MessageTransfer Session) with details (PDU information ID, N2 (PDU SM Session ID), QFI(s), QoS Profile(s), CNTunnel Info, S-NSSAI from the Allowed NSSAI Session - AMBR, PDU Session Establishment type, N1 SM container (PDUAccept ([QoS Rule(s) and QoS flow level QoS parameters if needed for the QoS flow(s) associated with the QoS rule(s)], selected SSC mode, S - NSSAI(S), DNN, allocated IPv4 address, interface identifier, Session - AMBR, selected PDU session type, [reflective QoS timer] available), [P - CSCF address(es)], [Always-on PDU SessionGranted). Multiple UPFs are used for the PDU Session. CNTunnel Info contains tunnel information re