Why didn't Apple 13 background software inform you?

Apple's mobile phone receives the message of prompt tone.

First, check whether the volume of the mobile phone is turned down. Sun Jiajun tries to raise the volume and check whether the mute button of the mobile phone is turned on. If it is turned on, turn off the mute button. If there is no problem, check the setting sound of the mobile phone and whether the SMS prompt tone is set in the release. If it is a reminder of myopia, it is also possible. If not, try to restart the phone. If it still doesn't solve the problem, try all the settings of the phone or restart the phone directly.