Or put the phone in silent mode,

Just see if the mute button or mute mode of Apple's mobile phone is turned on. If there is, turn off the mute button.

Second, it may be a problem with system settings. We can set to restore the mobile phone system, turn on the mobile phone, and then open "Settings" on the mobile phone's main screen.

Open the "General" option, then find the "Restore" option in the general list of the mobile phone, click Open, click and select the "Restore all settings" option to start the recovery, or restart the mobile phone.

Thirdly, if the above methods can't solve the problem, it may be that there is something wrong with the mobile phone firmware system, so just restore the mobile phone firmware system.

Fourth, finally, it may be a hardware problem. If it is a hardware problem, you need to send the phone to the after-sales service.