This application provides a communication method and apparatus, and a system, to protect security and user privacy in a data transmission process. After determining to establish a radio resource control (RRC) connection in anonymous mode, a terminal device sends a request to an access network device, to request to establish the RRC connection in anonymous mode, so that the access network device establishes the RRC connection in anonymous mode to the terminal device. The solutions in this application may be applied to a communications system, for example, may be applied to a 5th generation 5G network.