No mobile phones can be operated without the use of a small microchip called a “SIM” card. Most of the time your phone registers the SIM card as you insert it on your mobile phones. However, sometimes, network outages and other issues can cause SIM card communication errors.
Whenever your phone does not let your SIM connect to your provider’s network for any reason, you may receive “SIM Registration Failed” or “SIM Update Failed” notification on the top of your mobile’s screen.
Many times, the problem can be resolved without the help of a wireless company. Here is how you can fix a failed SIM card registration.
Power your device off.
Remove the SIM card. (For mobile phones, remove the battery and SIM card.) Wait a few moments.
Reinsert the battery (if applicable) and SIM card. Turn the device back on.
Verify that the device connects to the network — not the signal indicator icon. If it does not, contact your wireless service provider for assistance.