Xiaomi mobile phone can't recognize SIM card. What if there is no service?

Check whether the SIM card is installed correctly.

Send it to the original factory for repair.

SIM card is the abbreviation of (subscriber identity module).

GSM digital mobile phones are also called subscriber identification cards and smart cards, and they must be installed before they can be used. The computer chip stores the customer information of digital mobile phone, encryption key and user phone book, which can be used to identify the identity of GSM network customers and encrypt the voice information when customers talk.

SIM cards come in different sizes. The size of the original card (that is, when it was just acquired) was 54mm×85mm (the standard size of bank cards).

The application of SIM card in GSM system separates the card from the mobile phone, and the SIM card uniquely identifies a customer.