What if there is no prompt tone on OPPO mobile phone?

You can operate as follows: 1. Check whether the mute mode of the mobile phone is turned on: Settings-Sound and Vibration-Mute Mode-Complete Mute Function is turned on; 2. Check whether the phone has turned on the Do Not Disturb mode: Set-Do Not Disturb mode; 3. Has the mobile phone turned off the switch of the notification center: Settings-Notification Center-Information-Allow notification, status bar display, and screen lock display (at present, only ColorOS 2. 1 system has this function); 4. Whether to turn off information notification in mobile phone information settings: information-settings-information notification; 5. Check whether the contacts on the mobile phone are open. No reminder in this session: contact person-contact information-no reminder in this session.