1, first open the phone desktop and find the settings on the desktop.

2. Secondly, enter the home page of settings, and you can see the cellular network options.

3. Then, in the cellular data, find the cellular data option.

4. Then in the cellular network interface, click the voice and data options.

5. Later, in the voice and data interface, we chose to check 4g and turn on the VoLTE option.

6. Finally, go back to the settings, turn off the WLAN and use the 4g network.