An online signup method and an apparatus, the method including identifying, by a first core network element, that a terminal device needs to perform online signup, triggering, by the first core network element, online signup authentication of the terminal device, and sending, by the first core network element, in response to the online signup authentication of the terminal device succeeding, a first message to a second core network element, where the first message includes a first identifier of the terminal device, and requests that the second core network element generate or update a network subscription of the terminal device.