If you just updated your iPhone to iOS 9.3.1 and got the SIM Not Valid (invalid SIM) error. This is the easiest way to fix it.
Updating your iPhone or iPad to the latest iOS version can either be smooth or tricky. While Apple’s engineers and developers would test the iOS before releasing it to the public, getting some sort of error is still possible.
There were reports on Apple’s forum that some people are getting SIM Not Valid error message after updating to iOS 9.3.1. This is affecting newer devices such as iPhone 6s, iPhone 6 and the slightly older model iPhone 5s/5c.
It’s quite an odd problem because an iOS update wouldn’t usually affect the SIM card.
The error message which you may have encountered could be similar to the one shown above. Another possible error is shown below which is SIM Failure.
There may be some versions of SIM cards which are not tested with the latest iOS version. This is usually the root cause of the problem.
If you’re near an Apple Store, simply head to the nearest store with your iPhone to get your SIM card replaced. If there’s no Apple store near you, any carrier shop might be able to assist you with activating the iPhone by using a new and unused SIM card.
You may also want to try looking for any old SIM card around the house as there’s a possibility that it will work.
If all fails, there’s a high chance that your device’s activation policy has changed, that means it’s no longer tied to its original carrier e.g. AT&T changed to T-Mobile. This usually happens when you bought a used iPhone. In this case, you will need to do an IMEI check to find out the activation policy, and get it unlocked. Please contact us if you need any of these services.
If this solution helped you in any way, do leave your comments below and share your experience!