Apple's mobile phone rings inexplicably.

Notification sent by the program, close notification. Maybe an application sent a notification, such as SMS, social media, email, etc. , so there will be a notice reminder. You can enter the notification center of your mobile phone to see which application sent the notification. For applications that don't need to receive notifications, you can click notifications for that application, and then choose to close or unsubscribe. For applications that need to receive notifications, their notification methods can be adjusted, such as sound, vibration, reminder and so on.