A communication method, a communications apparatus, and a communications system, where the method includes: a first network element receiving identity information of a terminal from a second network element, where the identity information includes an identity of the terminal or an identity of a group of the terminal; the first network element obtaining, based on the identity information, type information of a serving network corresponding to the identity information; and the first network element sending API information of the first network element based on the type information. Based on this method, the second network element can select an available API based on the API information or the type information of the serving network and invoke the available API.