VoWiFi Mobile-Originated (MO) Call Creation Call Flow
This section describes the VoWiFi MO call creation call flow.

Step | Description |
---|---|
1 | UE requests for establishment of the IMS default bearer, PDU session, through PCF. After establishing the session, the UE receives the P-CSCF addresses from PCF. |
2 | The UE initiates the SIP signaling toward P-CSCF (AF). |
3 | The P-CSCF (AF) sends the NPCF Policy Authorization Update message to the PCF. |
4 | The PCF sends the NPCF SM Policy Control Update Notify Request to the SMF+PGW-C. |
5 | The SMF+PGW-C sends the NPCF SM Policy Control Update Notify Response back to the PCF. |
6 | SMF sends ChargingDataUpdateReq by including Multi-Unit-Usage with Rating-Group-Id that are received as part of Charging_Description of Sm_PolicyControl_UpdateNotify_Request to install PCC Rules. |
7 | CHF provides ChargingDataUpdateResp with Multi-Unit-Information for received Rating-Group values in requested message. CHF also provides params changes for Session-Level and Rating-Group values. |
8 | SMF sends N4 Session Modification Request to the UPF by including Create ULPDRs and Create ULFARs. Create ULPDRs include SDFs and QER Info which are received as part of PCC Rule Installation. |
9 | UPF responds back with N4 Session Modification Response to SMF by including Created ULPDR and Created ULFAR. Create ULFAR contains UL Tunnel Information of UPF for the dedicated bearer creation. |
10 | The SMF+PGW-C sends the GTPv2 Create Bearer Request to the S-GW. |
11 | The S-GW sends the GTPv2 Create Bearer Request to the ePDG. |
12 | IKE_CHILD_SA exchange happens between the UE and ePDG. |
13 | The ePDG sends the GTPv2 Create Bearer Response back to the SMF+PGW-C. |
14 | The established N4 session is modified between SMF+PGW-C and UPF+PGW-C. |
15 | The SMF+PGW-C sends the NPCF SM Policy Control Update Request to the PCF. |
16 | The PCF sends the NPCF SM Policy Control Update Response back to the SMF+PGW-C. |
17 | PCF sends the NPCF policy authorization notify request to P-CSCF (AF). |
18 | Establishes SIP-signaling and voice call between end-users through UE and P-CSCF (AF). |
Note |
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