Section: 5.34.8 Support for Cellular IoT
Content: This clause defines the specific impacts of deployments topologies with specific SMF Service Areas on how 5GS supports Cellular IoT as defined in clause 5.31. For a PDU Session supporting Control Plane CIoT 5GS Optimisation as defined in clause 5.31.4: - For a PDU session towards a DNN/S-NSSAI for which the subscription includes a NEF Identity for NIDD (i.e. for a PDU session which will be anchored in NEF), the AMF never inserts an I-SMF. When an I-SMF is inserted to serve a PDU Session, the I-SMF supports the features that, as specified in clause 5.31, apply to the V-SMF in the case of Home Routed. NOTE: This can require the SMF to subscribe onto I-SMF about RAT type change for a PDU Session as described in clause 4.23 of TS 23.502[ Procedures for the 5G System (5GS) ]  [3].