To fix this error message just follow this simple steps and everything should be working normally once you finish:
Step 1: Turn off the iPhone and remove the SIM card
Step 2: Turn the phone on, let it boot up, and slide to unlock your phone
Step 3: You should see the “No SIM card message, insert the GEVEY SIM
Step 4: Wait for the Gevey message, and click agree
Step 5: Wait 15 seconds, dial 112 and hang up in two seconds
Step 6: Go to settings and turn on Airplane Mode and wait 40 seconds for a message
Step 7: Turn of Airplane Mode and you should see another message
Step 8: Don’t touch or do another thing, just leave your phone without doing anything for at least 5 minutes
Step 9: The phone will eventually start picking up signal, the bars will start growing and the carrier name will appear
Step 2: Turn the phone on, let it boot up, and slide to unlock your phone
Step 3: You should see the “No SIM card message, insert the GEVEY SIM
Step 4: Wait for the Gevey message, and click agree
Step 5: Wait 15 seconds, dial 112 and hang up in two seconds
Step 6: Go to settings and turn on Airplane Mode and wait 40 seconds for a message
Step 7: Turn of Airplane Mode and you should see another message
Step 8: Don’t touch or do another thing, just leave your phone without doing anything for at least 5 minutes
Step 9: The phone will eventually start picking up signal, the bars will start growing and the carrier name will appear