Embodiments of this application provide a communications method, apparatus, and system. The method includes: A terminal device receives first information sent by a network device, where the first information includes access control information of services with N service attributes, and N is an integer greater than or equal to 1; and the terminal device determines, based on a first service that currently needs to be initiated and the first information, whether the terminal device can initiate the first service, where the N service attributes include at least a non-public network service, and the first service is any one of the services with the N service attributes. Therefore, access control on the terminal device is implemented when there is a non-public network service.