• Turn off the power and turn it on again.
• Turn off the power and remove the SIM card. Turn the power on again and check the service condition. The base station data are updated, and the normal services should be available.
• Upgrade to the latest software version.
• It may be a problem with a specific area or time. Move to another area and check if you experience the same problem.
• Call the customer center of the mobile telecommunications carrier and check the service status of the area.
• If the network signals are unstable, particularly in the subway or an elevator, the service may be interrupted momentarily.
• If you experience a problem with a phone call or data communication at a specific time or location, it may be a problem with a specific base station.
• The call may not be connected in a certain area or at certain times with many users around.
• The call service may be unstable if you move around the area where the base stations overlap.
• Data usage will be restricted if the mobile data usage limit is set.