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iPhone Says 'No SIM Card Installed'?

Time and again, Apple's flagship iPhones have come under the radar of the 'gadget police' and have been criticized for their design flaws. The most recent recurrence of this was when it was reported that the recently-released iPhone 6 handsets tend to bend because of intolerance to heat and pressure, that too when they are stored in the owner's pocket! When after spending exorbitant amounts of money on an exquisite mobile phone, that is the object of envy to everyone else, it is literally disappointing when it does not fulfill the basic purpose of utility.

While Apple works on improving upon its phone design, some of the people who own older iPhone 3G, 4, 4S, 5, 5C, and even 5S models are suffering from a common affliction; the "No SIM Card Installed" problem. If you are one of them, you need not despair, because we have the way you can fix it right here.


Detailed Analysis and Solutions

Did your iPhone, one fine morning, randomly declare that you have "No SIM card installed" on your device? You have every reason to be upset; however, by approaching the problem in a systematic, step-by-step manner, you can easily get to the root of the matter.

SIM Card Troubleshooting

Did you recently switch from a different mobile handset to an iPhone? And while doing so, did you yourself convert your SIM card to its smaller-sized counterpart by cutting it yourself? If the answer to any of the above is affirmative, chances are, you may have damaged your SIM card and need to request your carrier for a new one.
Even if you have no direct involvement in your SIM card's possible malfunctioning, it could have been damaged because of reasons like overheating. You could check if your SIM card is still a valid one, by inserting it into a different handset, that supports the same size of SIM card. If it is working there, then the key to this issue lies elsewhere.
You could also try to insert a completely different, compatible, and tested-to-be-working SIM card into the same device, and see if your iPhone recognizes it. If so, then the problem can be consolidated to your particular SIM card.
Maybe your SIM card genuinely has not been inserted correctly. Carefully remove your SIM card from your phone, by using a paper clip to pop out the SIM card tray. Then, reinsert it into the tray, and reboot your phone. If your SIM card has been positioned properly this time, it will be read, and your device will acknowledge it.
Maybe your SIM card is simply clouded with dirt or grime, or there may be fingerprints on the metallic chip, and that may be the reason that your device is unable to recognize it. To solve this problem, isolate it from the device once more, and using rubbing alcohol, clean the side that has the chip. Allow it to dry completely before you re-insert it.

Other Troubleshooting

Your SIM card physically may have nothing to do with the reason behind it not being recognized by your phone. The answer may lie with your device, firmware, or network connectivity.
If you are not able to connect to your network sometimes, your phone may assume that your SIM card is not valid. This happens with phones of all brands. Turn on the Airplane Mode of your phone, and after a few minutes, turn it off again. This will refresh your connectivity. You could also reboot your device entirely.
Check for any available carrier settings update. This can be done by opening Settings General About. If there is any update available, you will get to know it here.
Make sure that the SIM card tray of your iPhone is the one that came with the device when you purchased it from the vendor, and not the one you seated your SIM card on, when you inserted it into the iPhone you used earlier. Different iPhone models have differently manufactured SIM card trays.
Is your firmware up-to-date, or are you using an older version of iOS? Make sure you update your device to the latest version.
If your iPhone was functioning properly a couple of hours ago, and is displaying this suddenly, once you have ruled out the SIM card itself as a cause, but you are unable to pinpoint its actual cause although you are certain it is system-software related, the easiest thing to do is to restore your iPhone to a backed up version in which your SIM card is recognized.

The Last Resort

If none of the above methods result in the "No SIM Card Installed" problem's resolution, you may be facing this problem because of a design flaw that is present in many iPhone devices.
The SIM card tray's ejecting mechanism has a metal face, and sometimes, it comes in direct contact with the metallic part of the inserted SIM card (the chip), causing a short circuit to occur. As a result of this, it will not be possible for the device to recognize your SIM card.
To resolve this, a method employed by many frustrated, yet innovative users is to stick a small piece of Scotch tape (or any kind of tape) on the side of the SIM card tray. This will serve the purpose of isolating the SIM card from the metal part of the mechanism, and allow your device to recognize it, resolving the problem

The problem will most probably be resolved if you follow our step-by-step guide. However, if it still persists, you could contact Apple Support, or take it down to the nearest iStore. If the problem of SIM card failure occurs due to the design flaw, and your iPhone is still under warranty, you could in fact get the device itself replaced.