This application relates to the communications field, and discloses a communication method and a communications apparatus, so that a terminal device can register with a network through another network. The communication method is performed by a first access and mobility management function network element, including: receiving a first message from a terminal device, where the first message includes first identification information of the terminal device, and the first access and mobility management function network element is located in a first network; obtaining second identification information of the terminal device based on the first identification information; and sending a second message to a second access and mobility management function network element located in the second network, where the second message is used to request to register the terminal device with a second network, the second message includes the second identification information.