Check SIM card

1, whether the SIM card is inserted correctly. 2. Whether the SIM card is inserted incorrectly, such as the standard version of the telecom SIM card. 3. Enter the hardware test to see if the SIM card works normally (enter *#*#64663#*#* in the dialing interface). If the SIM card status is normal, go to step 5; If the status is unknown, go to step 4.

Check the SIM card status.

4. Try to change a different SIM card. If the status is still unknown during hardware testing, it is recommended to go to the maintenance point for testing. If the detection status is normal, the operator is advised to replace a SIM card (SIM card may be aging).

Check the network type

5. Whether the network type is correct and whether the operator chooses automatic. (Unicom preferred 3G, mobile preferred 2G, and telecom preferred automatic).

Check CDMA automatic network type

6. If the network type of telecom mobile phone is CDMA automatic, the problem can be solved by changing the network type to "WCDMA preferred" in the mobile phone information (* # * # 4636 # * *).

Check signal

7. Whether there is no signal in this area. You need to check whether other mobile phones on the same network have a signal.

Backup data

8. Back up the data, brush to the latest system version and try again.

Send it for repair

9. If the above methods still can't help you solve the problem, it is recommended to send the mobile phone to a nearby Xiaomi after-sales outlet or mail it to the maintenance machine online for testing.