Embodiments of the present invention provide a method for accessing a communications network by a terminal, an apparatus, and a communications system, relate to the communications field, and can effectively reduce a resource waste on a network side that is caused when WLCP is triggered by a malicious application on a terminal. A first message sent by a second device is received, where the first message includes a second message and an authentication parameter, the authentication parameter is a token or a User Datagram Protocol UDP port number, and the second message includes the encrypted authentication parameter; or the first message includes a second message, and the second message includes an encrypted authentication parameter; or the first message includes a second message and an authentication parameter; and the second message is sent to a terminal.