One disclosure of the present specification provides a method by which a wireless device transmits an RRC message. The method can comprise the steps of: allowing, an AS layer of the wireless device, to acquire an NAS signaling request message, an RRC establishment cause field, and a call type field from an NAS layer; checking the acquired RRC establishment cause field and the call type field; determining, when the NAS signaling request message includes user data according to an optimization plan through a control plane, whether to perform or skip an examination for access blocking (AB) based on the RRC establishment cause field and/or the call type field; and transmitting, when blocking is not achieved or when the examination is skipped according to the examination result, an RRC connection request message to a base station so as to transmit the NAS signaling request message including the user data.