Unicom's mobile phone card suddenly stopped serving.

Mobile communication is to send and receive signals through the network base station, and then communicate with the called party. If the mobile phone shows no service, it may be related to the following situations:

1. The contact between the SIM card of the mobile phone and the elastic sheet of the mobile phone card slot is poor, which causes the circuit of the SIM card to fail to work and the mobile phone cannot communicate with the network base station. At this time, you can take out the SIM card, wipe the gold finger of the SIM card with a clean cotton cloth and reinstall it.

2. The system software turns off the modem in the signal processing circuit of the mobile phone because the installed application software is incompatible with the system. At this time, the phone can be turned off and restarted, and the modem in the phone signal circuit will be restarted. After the signal is normal, the suspicious mobile phone application software installed before the problem occurs will be deleted.

3. The SIM card of the mobile phone is not registered in the network. At this point, you can insert this SIM card into another mobile phone. If it still shows that there is no service, that is the reason for the SIM card.

4. Due to unexpected reasons, the SIM card of the mobile phone failed to reconnect to the search network after there was no signal in the network signal coverage area. At this point, you can manually search for network registration again under the menu of Settings-General-Network-Network Operator.

5. The reason why the signal coverage of the mobile phone SIM card network operator is not enough, at this time, you can change the location to an open area, and then check the display of the mobile phone signal grid. If the display is normal after changing the location, you can call the service phone of the network operator for feedback and complaint.

6. The calling card has been used for too long. With a valid certificate, you can reissue a card at the local business hall.