There is no service and search in the upper left corner of iphone7 ... no 4G calls, no calls, no messages? urgent

I have been looking for it because there is no signal on my mobile phone. Check the cause and solve the problem:

1. Check whether the sim card is inserted in the mobile phone: you need to insert the sim card to connect the signal.

2. Check whether the mobile phone card slot or sim card is damaged: you can try to insert another mobile phone card, and then put the sim card of the mobile phone itself on another mobile phone to see if there is a signal. If the card slot is damaged, it is recommended to replace the card slot. If the sim card is damaged, please replace it in the business hall.

3. Mobile phone shutdown due to network delay: you can turn on the mobile phone flight mode, turn it off after five seconds, or restart the mobile phone.

4, where the signal is not good, you can search elsewhere if you can't find the signal.

5. The card sticker is not installed or damaged: some locked mobile phones need to cooperate with the card sticker to search for signals. Please install the card sticker and use it. If the card sticker is damaged, please replace the card sticker.