It's not often that an iOS 7.x upgrade goes wrong but ‘bad luck Brian' does strike once in a while. Sometimes, users end up with the dreaded “Invalid SIM” or “No SIM” error after an iOS upgrade. Did you upgrade to iOS 7.0.x and all of a sudden find that your SIM is being called “invalid”?
There are no clear fixes for this problem but there certainly is a list of things you can try to get around this error. In most cases, simply removing and replacing the SIM tray seems to be the trick to get things rolling again but occasionally, that doesn't work. That calls for a closer inspection.
1. Remove SIM, Replace Again
Like mentioned before, try this simple thing first. Remove the SIM tray from the iPhone, remove the SIM card from the tray. Then, place it back and insert the SIM tray into the iPhone. For a good measure, reboot the iPhone completely. Check if the iPhone picks up the SIM card correctly and displays the name of the carrier and the signal bars (circles?).
2. Reset Network Settings
One trick that has worked for a lot of people who have faced SIM-related issues is resetting network settings. To do this, all you've got to do is this:
Go to Settings → General → Reset → Reset Network Settings. Your iPhone will do a short respring and if you're lucky, the Invalid SIM problem should be resolved by now.
3. Change the SIM Card
If your SIM card worked on older iPhones (or other phones) and is not working with a new iPhone, chances are equally high that the SIM card is chipped or damaged somewhere. It's a tiny thing and a little scratch can actually render it useless.
Speak to your carrier and get a new SIM card (replace the old one) and test it on your iPhone.
4. Restore iPhone
This is not exactly a pleasant workaround but a restore should definitely be one of the things you've tried to correct the Invalid SIM or No SIM error. It's more of a formal obligation because when you talk to Apple Support or even your carrier to get this thing resolved, they ask you – invariably – to try restoring the iPhone again. It's better that you try it.
A clean restore is always preferred. Take a backup your iPhone via iTunes and then do a clean restore – meaning, don't restore to the backup. Restore as new. Then, test the SIM. If it works, well and good and you can restore from the backup now.
5. Test the SIM on other iPhones
A cool way to test if the SIM card is working correctly is to use it on another iPhone (preferably an unlocked one). This can be hard if your friends do not have an iPhone which supports your SIM card (nano, micro etc.). But where there is a possibility, make sure you've tested the SIM card on other iPhones too for good measure.
6. Take it to the Apple Store
The last resort, of course, is to take your device to Apple Support. In rare cases, it's a device issue that prevents the SIM card from being identified. Under this circumstance, Apple will replace your iPhone – for free if it's under warranty.
We're actively looking for all kinds of solutions that have worked for people across the globe. The Invalid SIM or No SIM problem is like all software issues: you don't always know where the problem is but there is a workaround. If you faced and then solved this issue, let us know how you did it. Thanks!