A communication method, comprising: obtaining, by a terminal device, instruction information sent by a core network device, wherein the instruction information is used to instruct the terminal device to communicate with an application server through an access network device corresponding to a first radio access technology, RAT, wherein the instruction information is carried in a broadcast configuration message and the broadcast configuration message comprises an area where the terminal device communicates with the application server, wherein the area refers to an area where the terminal device receives broadcast information by using the access network device corresponding to the first RAT; selecting, by the terminal device, the access network device corresponding to the first RAT based on the instruction information; and communicating, by the terminal device, with the application server by using the selected access network device corresponding to the first RAT; wherein, the terminal device supports Internet of Things, IoT, services and supports communication with the application server through at least two RATs, and the at least two RATs comprise the first RAT and a second RAT; wherein the communicating, by the terminal device, with the application server by using the selected access network device corresponding to the first RAT comprises: after obtaining the instruction information, only using the selected access network device corresponding to the first RAT to communicate with the application server; and receiving, by the terminal device, the broadcast information from the application server by using the selected access network device corresponding to the first RAT. obtaining, by a terminal device, instruction information sent by a core network device, wherein the instruction information is used to instruct the terminal device to communicate with an application server through an access network device corresponding to a first radio access technology, RAT, wherein the instruction information is carried in a broadcast configuration message and the broadcast configuration message comprises an area where the terminal device communicates with the application server, wherein the area refers to an area where the terminal device receives broadcast information by using the access network device corresponding to the first RAT; selecting, by the terminal device, the access network device corresponding to the first RAT based on the instruction information; and communicating, by the terminal device, with the application server by using the selected access network device corresponding to the first RAT; wherein, the terminal device supports Internet of Things, IoT, services and supports communication with the application server through at least two RATs, and the at least two RATs comprise the first RAT and a second RAT; wherein the communicating, by the terminal device, with the application server by using the selected access network device corresponding to the first RAT comprises: after obtaining the instruction information, only using the selected access network device corresponding to the first RAT to communicate with the application server; and receiving, by the terminal device, the broadcast information from the application server by using the selected access network device corresponding to the first RAT. after obtaining the instruction information, only using the selected access network device corresponding to the first RAT to communicate with the application server; and receiving, by the terminal device, the broadcast information from the application server by using the selected access network device corresponding to the first RAT.