VoNR Paging Policy Differentiation Procedure
This section describes the VoNR Paging Policy Differentiation procedure.

Step |
Description |
---|---|
1 |
The SMF enables Paging Policy Differentiation (PPD) under DNN profile based on DNN, 5QI, and PLMN. |
2 |
The SMF performs the PDU session establishment as described in VoNR PDU Session Creation Call Flow section, and fetches the P-CSCF addresses for sending it to the UE. The SMF programs UPF with PPD for the respective PDU session as part of N4 interface by provisioning flows, and traffic detection information for every PDR. |
3 |
The UPF detects if any Downlink (DL) Packet is set with \nDSCP value (TOS in IPv4 / TC in IPv6) when PPD is enabled for the PDU session. |
4 |
The UPF detects that there is no forwarding path as there is no N3 Tunnel for the DSP marked DL packets. |
5 |
The UPF sends Data-Notification (QFI, DSCP in TOS (IPv4) / TC (IPv6) in packet header). |
6 |
The UPF enables DL Data buffering based on the buffering configuration. The UPF sends Data Notification (N4 Session ID, Information to identify the QoS Flow for the DL data packet, DSCP) message to the SMF.
|
7 |
The SMF determines the AMF and invokes the Namf_Communication_N1N2MessageTransfer to the AMF including the PDU Session ID based on N4 Session ID. The SMF, while waiting for the User Plane Connection to be activated, receives additional Data Notification message. The SMF derives a different Paging Policy Indicator according to the additional Data Notification or the DSCP of the data packet. The SMF invokes a new Namf_Communication_N1N2MessageTransfer indicating the higher priority or different Paging Policy Indicator to the AMF. When supporting Paging Policy Differentiation, the SMF determines the Paging Policy Indicator related to the downlink data that has been received from the UPF or triggered the Data Notification message, based on the DSCP as described in 3GPP TS 23.501, section 5.4.3. The SMF indicates the Paging Policy Indicator in the Namf_Communication_N1N2MessageTransfer. |
8 |
The AMF sends Namf_Communication_N1N2MessageTransfer response to the SMF with a cause “Attempting to reach UE" if the UE is in CM_IDLE State. If the UE is in CM-CONNECTED state, then the AMF sends a Namf_Communication_N1N2MessageTransfer response to the SMF immediately with a cause "N1/N2 transfer success". |
9 |
The SMF sends Failure Indication to the UPF on receiving a negative response from AMF. |
10 |
The AMF initiates paging towards the UE through the (R)AN. |
11 |
The AMF initiates NAS Notification towards the UE. |
12 |
The AMF notifies the SMF by sending Namf_Communications_N1N2MessageTransfer Failure Notification to the Notification Target Address provided by the SMF if the UE does not respond to paging. The AMF is unaware of an ongoing Mobility Management (MM) procedure that prevents the UE from responding. The AMF receives an N14 Context Request message indicating that the UE performs Registration procedure with another AMF. |
13 |
If the UE is in CM-IDLE state, upon receiving a paging request for a PDU session associated to 3GPP access, the UE initiates the UE Triggered Service Request procedure as defined in 3GPP TS 23.502, section 4.2.3.2. |