(R)AN to UE: The RAN performs RRC Connection Reconfiguration with the UE depending on the QoS Information for all the QoS Flows of the PDU Sessions whose UP connections are activated and Data Radio Bearers. For UE in CM-IDLE state, the User Plane security is established at this step, which is described in detail in TS 38.331 
and TS 36.331 
If the N2 Request includes a MM NAS Service Accept message, the RAN forwards the MM NAS Service Accept to the UE. The UE locally deletes context of PDU Sessions that are not available in 5GC.
NOTE 2: The reception of the Service Accept message does not imply the successful activation of the User Plane radio resources.
NOTE 3: In case not all the requested User Plane AN resources are successfully activated, TS 38.413 
will define how to handle this.
After the User Plane radio resources are setup, the uplink data from the UE can now be forwarded to RAN. The NG-RAN sends the uplink data to the UPF address and Tunnel ID provided in the step 4.