N9 Home Routed Roaming Call Flow
This section describes the N9 Home Routed Roaming call flow.

Step |
Description |
---|---|
1 |
The UE sends the Create PDN Request to AMF. |
2, 3a, 3b |
AMF performs the SMF selection and sends Nsmf_PDUSession_CreateSMContext_Request to vSMF and receives response. |
4 |
vUPF performs the UPF selection. |
5a, 5b |
vSMF sends the N4 Session Establishment Request to vUPF and receives a response from it. |
6 |
vSMF sends Nsmf_PDUSession_Create_Request to the hSMF. |
7 |
Registration or subscription data retrieval is performed. |
8 |
PDU session Authentication or Authorization procedure is performed. |
9-13 |
See 3GPP TS 23502, version 15.4.0, section 4.3.2.2.2. |
14 |
vSMF sends Namf_communication_N1N2MessageTransfer to SMF. |
15, 16 |
AMF sends N2 PDU Session Request to RAN and receives a response. |
17, 18 |
AMF sends Nsmf_PDUSession_updateSMContext_Request to vSMF and receives a response. |