No Sim Card?

Does this situation sound familiar to you?

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 not an issue unique to the iPhone 7. There have been complaints about the same message on the iPhone 4, the iPhone 5, and more recently on the iPhone 6.

And the problem isn't even unique to the iPhone; people are making the same complaints about other phones that use SIM cards.

Why Does My Phone Not Accept the SIM Card?

It is hard to pinpoint the exact reason as to why iPhones that use a SIM card display error messages at random times. Sometimes it is a simple glitch which cannot 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 scenario, the SIM card could be defective, and that would require you to get a new SIM card to install on the phone.

You are not alone, and there are a few things you can do yourself, for free, to diagnose the cause and solve it.

How to Fix an iPhone When it Says "No SIM Installed"

Here are some steps you can take to fix the issue. If these steps do not work, you may need to contact Apple directly for support.

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.
Install the Latest iOS: Sometimes all you have to do is go into the settings and install the most up-to-date version of the iOS. Apple is always working on bug and error fixes, and a new version of the OS can help fix SIM card issues that arise from corruptions in the software.
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.
Hard Reset: 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, while it is in airplane mode, do a hard reset, and then once it turns on again take it off "Airplane Mode."
Reset Network Settings: Go 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.
Check on Your Mobile Account: Make sure that your account is up to date, valid, and active with a phone company. If your phone service has been terminated or suspended that could be the reason your SIM card no longer works.

Apple Recommendations

Apple also advises that you should ensure that the following areas have been considered:

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.

Android Phone Says no SIM Card Installed

This SIM card problem is not unique to iPhones, many Android users also experience the same issue. The process is essentially the same for Android phones: try following the same steps to restart the phone, install a new OS update, clean out the SIM card slot. If these steps do not work try contacting technical support.

SIM-Free iPhone

There are some phones that do not use a SIM card at all. Instead of using a SIM, these phones have an electronic serial number that is tracked by the phone carrier, so there is no need to store the information on a SIM card as the carrier has a list of all the phones in use in their network.

SIM cards are not used in great numbers in the United States but they are the preferred type of phone internationally.

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.