Oppo SMS has no sound.

This is because the SMS permission notification function is not turned on.

Here, taking the OPPO R9S mobile phone as an example, the method to turn on the SMS operation notification function is as follows:

First, click "Settings" on the phone desktop.

2. Then select the "Notification and Status Bar" option in the setting interface.

Third, then open "Notification Management" to enter.

4. After entering, find the "information" item in the application list and click Enter.

5. Then turn on the switches of "Allow notification" and "Notify ringtone and vibration".