Why Does My iPhone Say "No Sim Card Installed"?
You have been using your iPhone without any concerns, and then all of a sudden you are presented with a message that says ‘No SIM card installed’, ‘Invalid SIM’ or ‘Insert SIM’
This is definitely not an issue unique to the iPhone 4. There have been complaints about the same message on the iPhone 3GS, the iPhone 3G and more recently on the iPhone 5.
And the problem isn't even unique to the iPhone; there are people making the same complaint about other phones that use SIM cards.
Why Does this Message Occur?
It is hard to pinpoint the exact reason as to why phones that use a SIM card display error messages at random times. Sometimes it is an unfortunate simple glitch which can not be fully explained and at other times it is due to an issue with the iPhone being too hot or the presence of dust on the SIM card itself. Worst case, it could be a faulty SIM.
You are not alone, and there are a few things you can do yourself, for free, to diagnose the cause and usually solve it.
How To Fix an iPhone When it Says 'No Sim Installed'
Whenever this happens there are a few things you can do:
Restart: Hold down the Sleep/Wake button at the top for a few seconds and slide to power off. After a few seconds, turn on your iPhone again.
SIM Tray Closed: Make sure that the SIM card tray on the side of your phone is completely closed. If it is not, the card may not be fully slotted in.
Remove and Reinstall SIM: Use the device that came with your iPhone to remove the SIM. If you no longer have that you should be able to use a paperclip. Eject the SIM tray on the side of the iPhone, take out the SIM card, put it back in again, and then replace the SIM tray.
Reboot: Hold down the Home button and the Power button simultaneously until the Apple icon appears. Then wait a few seconds and turn it on again.
Airplane Mode: Put your iPhone into 'Airplane Mode' and toggle it on and off. If that does not work, whilst it is in airplane mode, do a hard reboot, and then once it turns on again take it off 'Airplane Mode'.
Reset network settings: Go to to Settings > General > Reset > Reset Network Settings.
Dust particles: In some cases cleaning the SIM card and removing any dust from inside the SIM socket of the phone can solve your problems.
Apple also advises that you should ensure that the following areas have been considered:
- Make sure your phone is on the latest version of iOS.
- Check to see if there is an update for your carrier by going to Settings > General > About. If an update is available, a prompt will appear.
- Restore the iPhone by connecting it to a computer and re-syncing with iTunes.
Testing for a Malfunctioning SIM Card
It is also possible that your SIM card could be malfunctioning. One easy way to test this is to try inserting it into another phone or placing someone else's SIM in your phone.
Of course when we are talking about iPhones we need to make sure that we are using similar SIM cards (micro, nano, etc.).
If a different SIM works in your phone, and the No SIM warning message disappears, then it is very likely that yours is broken.
Alternatively, if trying another SIM doesn't solve your problem, you may need to call Apple or visit your local Apple Store.
New SIM: Return your SIM card to the phone dealer where you got it or to your network dealer for a replacement.