Voice service processing method and terminal device

1. A voice service processing method, wherein the method comprises:

sending, by a terminal device, a first message to a network device of a first network, wherein the first message requests a circuit switched fallback (CSFB) voice service;

receiving, by the terminal device, a second message sent by the network device of the first network, wherein the second message instructs the terminal device to perform network redirection;

with the second message carrying no frequency information of a second network for the network redirection, determining, by the terminal device, a redirection frequency, wherein the redirection frequency is a frequency supported by the second network, and internally constructing, by the terminal device, a message that carries the redirection frequency; and

sending, by the terminal device based on the redirection frequency obtained from the internally constructed message carrying the redirection frequency, a connection request to a network device of the second network, to perform a circuit switched (CS) voice services,

wherein the determination of the redirection frequency comprises:

obtaining, by the terminal device, historical frequencies, wherein the historical frequencies are frequencies that are used to access the second network by another terminal device in a process in which the another terminal device is handed over from the first network to the second network, and a location area of the another terminal device is the same as a current location area of the terminal device.

2. The method according to claim 1 , wherein the determination of the redirection frequency further comprises:

determining, by the terminal device, one of the obtained historical frequencies as the redirection frequency.

3. The method according to claim 2 , wherein the location area of the another terminal device is a location area of the another terminal device in the process in which the another terminal device is handed over from the first network to the second network.

4. The method according to claim 2 , wherein the obtaining, by the terminal device, of the historical frequencies comprises:

receiving, by the terminal device, the historical frequencies sent by a cloud server.

5. The method according to claim 1 , wherein the method further comprises:

saving, by the terminal device, a correspondence between the first network and the redirection frequency.

6. The method according to claim 1 , wherein the first network is a Fourth Generation Mobile Communications Systems (4G) network, and the second network is a Second Generation Mobile Communication Systems (2G) network.

7. A terminal device, comprising a processor, a memory, and a transceiver, wherein the processor, the memory, and the transceiver are connected by using a bus system;

the memory is configured to store instructions;

the transceiver is controlled by the processor to receive and send a message, to implement communication between the terminal device and a network device; and

the processor is configured to invoke the instructions stored in the memory, to make the terminal device perform:

sending a first message to a network device of a first network, wherein the first message requests a circuit switched fallback (CSFB) voice service;

receiving a second message sent by the network device of the first network, wherein the second message instructs the terminal device to perform network redirection;

with the second message carrying no frequency information of a second network for the network redirection, determining, by the terminal device, a redirection frequency, wherein the redirection frequency is a frequency supported by the second network, and internally constructing, by the terminal device, a message that carries the redirection frequency, and

sending, based on the redirection frequency obtained from the internally constructed message carrying the redirection frequency, a connection request to a network device of the second network, to perform a circuit switched (CS) voice service,

wherein the determination of the redirection frequency comprises:

obtaining, by the terminal device, historical frequencies, wherein the historical frequencies are frequencies that are used to access the second network by another terminal device in a process in which the another terminal device is handed over from the first network to the second networks, and a location area of the another terminal device is the same as a current location area of the terminal device.

8. The terminal device according to claim 7 , wherein the determination of the redirection frequency further comprises:

determining, by the terminal device, one of the obtained historical frequencies as the redirection frequency.

9. The terminal device according to claim 8 , wherein the location area of the another terminal device is a location area of the another terminal device in the process in which the another terminal device is handed over from the first network to the second network.

10. The terminal device according to claim 8 , wherein the obtaining of the historical frequencies comprises:

receiving, by the terminal device, the historical frequencies sent by a cloud server.

11. The terminal device according to claim 7 , wherein the processor is further configured to invoke the instructions to make the terminal device perform:

saving a correspondence between the first network and the redirection frequency.

12. The terminal device according to claim 7 , wherein the first network is a Fourth Generation Mobile Communications Systems (4G) network, and the second network is a Second Generation Mobile Communication Systems (2G) network.