Section: 4.2.10.2 SMF triggered N3 data transfer establishment procedure
Content: If UE and AMF successfully negotiate N3 data transfer in addition to Control Plane CIoT 5GS Optimisation based on the Preferred and Supported Network Behaviour as defined in clause 5.31.2, then the SMF may, e.g. based on the amount of data to be transferred or due to congestion, initiate N3 data transfer establishment procedure for any PDU session for which Control Plane Only Indicator was not included. The SMF triggered N3 data transfer establishment procedure may be initiated by the SMF while the UE is in CM-IDLE or CM-CONNECTED state and follows the Network Triggered Service Request procedure defined in clause 4.2.3.3 with the following differences: Step 3a. The SMF request the activation of Data Radio Bearer and N3 tunnel for the PDU session in Namf_Communication_N1N2MessageTransfer. Step 3b. If the RAT type is NB-IoT and the UE already has 2 PDU Sessions with active user plane resources, the AMF shall not proceed with the rest of the procedure and instead the AMF shall respond with Namf_Communication_N1N2MessageTransfer Response with appropriate failure message. Step 6. The UE triggered N3 data transfer establishment procedure defined in clause 4.2.10.1 is applied instead of Service Request procedure from clause 4.2.3.2. Step 7. When the N3 data transfer is set up for a PDU session, the UE and the network shall only use user plane radio bearers to transfer data PDUs on that PDU Session.