What is the reason why there is no prompt tone when vivo mobile phone receives SMS? What should I do?

This is because the mobile phone does not turn on the SMS permission notification or screen lock notification function.

Here, take VIVO X9 mobile phone as an example, and the setting method is as follows:

First click the "Settings" icon on the phone desktop, as shown in the figure below.

2. After entering the setting interface of the mobile phone, drop down the menu, and then select the "status bar and notification" option, as shown in the figure.

Third, open "Information" in the status bar and notification interface, as shown in the figure.

4. Finally, in the information interface, open all the options in the red box below, as shown in the figure.