Many times you have seen “ No SIM alert on iPhone & iPad”, “Invalid SIM” or “No SIM Card installed” after entering a card in iPhone and iPad slot. In this can you can find the exact solution for this problem. So you must have to follow the below steps given here one by one.
Solution steps on No SIM alert on iPhone and iPad
1# Update iOS in your iPhone, iPad. Before that, you have to take backup your data using iTunes or iCloud.
2# Enable/ Disable (Turn on or Turn off) Airplane mode from the control center or Under the Setting > Airplane mode.
3# Restart your device, by a press and hold only Sleep button till the red slider appear. And slide it from left to right.
4# Up to date career setting, At the time of new career you will get a small setting file which should be updated when your SIM changed, To find out Go to the Settings > General > About. If any update available then you can see update button in place of OK.
6# if you have any extra or AlterNet SIM card or Other’s card then try with it. Then it will work then contact your career provider and make sure your card is valid or not out of service and due date period.
7# you have an old backup then find it and restore it Might be it will cause of new iOS update. Recently many iPhone fans faced “ No SIM alert on iPhone ”.
Apple Also helps to solve your problem regarding No SIM alert on iPhone or SIM not valid, So you can directly contact with Apple Support center from here.