The SMF communicates with the Unified Data Management (UDM) and Policy Control Function (PCF) to do the following:
* Procure the subscribed and authorized QoS parameters for the Guaranteed Bit Rate (GBR) and non-GBR flows
* Pass the relevant information to the UE (NAS), gNB (NGAP), and UPF (PFCP)
This ensures that all nodes on the network provide the desired QoS to the PDU session
The SMF uses the service-based N7 interface with the PCF to retrieve the session management policy information corresponding to the PDU session of the UE. The SMF selects the PCF during the PDU Session Establishment procedure. It also acts as a consumer of the PCF-provided session management policy service.
