Insufficient phone bill or expired subscription.
First, confirm whether the mobile phone is turned off. Is the phone bill insufficient or the package expired?
Poor position
Secondly, check your position. Is it on the train, in the valley or in other places where the network signal is not very good?
Sim card problem
In addition, there may be something wrong with the sim card. Check whether the sim card is inserted correctly and whether the card slot is damaged. You can try using another mobile phone card, or put your sim card on another mobile phone.
network delay
If the phone is down due to network delay, you can try to turn on the flight mode for five seconds and then turn it off, or simply restart the phone rudely.
Advantages of Apple's mobile phone
The benefits of Apple's mobile phone are numerous! High quality, long service life, brand influence and exquisite craftsmanship are unmatched by other mobile phones.