1. Turn off the phone and restart to re-search the network to try.
2. If it is a dual SIM card phone, please check whether the SIM card is activated: Settings - SIM card manager - SIM1/SIM2 - click the SIM card icon - slide to open (the operation of different models of cell phones may be slightly different).
3. If there is still no signal, it is recommended to turn off the phone and remove the SIM card, wipe the SIM card chip with an eraser, and then reinstall it.
4. If this is not effective, please try another location to rule out whether it is due to poor signal coverage in your location.
5. Try changing the network mode to 3G or 2G (without selecting Auto Connect mode). Note: Changing the network mode is not supported on some devices.
6. Try changing to another SIM card.
7. Update the system version of your phone: Settings-About phone (About device)-Manually download update/Automatically download update (Software update/System update-Update). Note: Please backup the data (contacts, messages, pictures, etc.) in your device before upgrading.
If there is still no signal or emergency call after the above operation, please bring the purchase invoice, warranty card and the machine to the nearest service center for inspection.