Provided is a method for a wireless device for transmitting an RRC message according to one disclosure of the present specification. The method may comprise a step for an NAS stratum of the wireless device transmitting an NAS signaling request message to an AS layer to transmit the former to a network node. The NAS signaling request message can comprise therein an indication of one or both preferred or required plans from among the plans for optimizing the EPS for CIoT using a control plane (CP) or a user plane (UP). The method may comprise a step for the NAS stratum of the wireless device receiving, from the AS stratum, an NAS signaling acceptance message or NAS signaling rejection message from the network node.