Often happens so that after a long period of use your iPhone suddenly ceases to identify the SIM card and begins to issue a message about its absence. Most often this happens after the fall of the device or some kind of its sharp shake. Ironically, this problem is not so rare on Apple devices. Do not be scared: if your iPhone does not see the SIM card, it does not mean that it broke, most likely it's just a small program crash, which is easy to fix.
The simplest ways to solve the problem
To begin with, it is recommended to try simply to pull out the SIM card and insert it into the device again. If this is a normal temporary failure, then this method should help. If the iPhone does not see the SIM card further, we try to reboot the device and check to see if the error has been corrected. If the problem persists, it is possible that the cause of the error is not the machine itself, but a SIM card. Find another one and try to turn on the phone by installing it. If your other iPhone is working properly - you can safely contact your operator for a free replacement.
Changes in the software
If the previous tricks did not work, and the iPhone does not see the SIM card as before, we try to solve the problem with the help of changes in the software. For example, you can perform firmware firmware. If the iPhone does not see the SIM card after the upgrade, try to roll back the operating system to the previous version. Most likely, these methods will help you to return your favorite smartphone to life.
The most "dangerous" reasons
If none of the above methods helped you, then, most likely, your iPhone stopped seeing the SIM card as a result of its incorrect use. Perhaps you are a fan of using your smartphone while taking a bath? This is to be abandoned once and for all: evaporating, moisture can penetrate into the smallest cracks in the phone casing and spoil the contacts on the microcircuits. It is possible that the contacts hit the water. Another serious reason why the iPhone does not see the SIM card, maybe its fall on asphalt (or any hard surface) and damage to the SIM reader. In both of these cases, only experienced masters in the service center can help you, you will have to take the phone for repair.
Feature of Apple devices
Some manufacturers "sew" in their device a special binding to a particular communications operator. The rest of the SIM cards the device simply does not detect. If your freshly purchased iPhone is locked at the request of the company, then you have nothing else to do but hand it back to the store. Of course, you can buy a special chip for unlocking, but it will be easier to buy a device that is not blocked for telecom operators elsewhere. To avoid such problems, try to treat your smartphone with care, do not let it fall, get moisture and download suspicious applications. Be careful.