My smartphone does not recognize the SIM ... here's how! A phone that does not recognize the SIM card (or "chip" as it is commonly known) is a common and rather annoying problem. There are several possible causes for this, and some "detective work" is needed to determine the exact culprit.
Fortunately, most cases have a simple solution. So if your smartphone does not recognize the SIM card, you may find the solution below.
The phone does not recognize the SIM… here's how!
“SIM card not detected” or “SIM card removed” how to fix on Android phones
Do you use an adapter? Try to change it
Adapters are quite common among smartphone users. They allow you to use one SIM card format (such as a Nano SIM) on a smartphone that requires another format (such as a micro SIM or a "normal" SIM).
So common, in fact, that if you go to a telephone operator today and buy a SIM card, you will probably get a "triple cut" card with a Nano SIM surrounded by two plastic frames, the adapters are suitable for smartphones using other formats .
Because they are simple thin pieces of plastic, adapters can wear out or deform over time, causing the card to misalign with the device's internal contacts, which will not be able to recognize it.
The solution is simple: replace the adapter. This is quite common. But if it doesn't work… read on.
If the phone does not recognize the SIM, try cleaning the contacts on the card
Dirt on the card's gold contacts can also cause problems. A simple solution for this is to take a hard white school eraser and gently rub it on the contacts until they are shiny again. This should be enough to remove any accumulated oxidation.
An alternative is to use a cotton ball dipped in a drop of isopropyl alcohol instead of 99% or more in place of the gum. Again, gently rub the cotton swab on the contacts and wait for the alcohol to evaporate completely before reinserting the card into the smartphone.
Warning: in this procedure never use alcohol gel or "household" alcohol. These products contain large amounts of water (30 to 54%!), Which can cause more oxidation and aggravate the problem. And never apply alcohol directly to your smartphone.
Hasn't it worked yet? So… let's proceed!
Test your SIM on another phone
It's easy: remove the card from your smartphone and insert it into another device, it's the most important piece of advice to listen to. If the SIM is not recognized, it is defective. In this case, go to your carrier's shop and ask for a replacement. This usually costs around € 10, you don't have to wait more than a few minutes.
If the card works on another device, the fault could be on your smartphone. In this case… go ahead.
If your phone doesn't recognize the SIM, try another SIM on your smartphone
Put a SIM that you know works on another device on your smartphone. It should be recognized. If not, it is very likely that the defect is in your device: the contacts between the card and the phone pins could be deformed, compromising the connection. In this case, the best thing to do is to call the manufacturer's technical support.
Some suggest placing a piece of thin paper or cardboard behind the card before inserting it into the device. The idea is to make the card "thicker" and force it against the contacts. Don't ever do it!
If your smartphone has a “drawer” slot, you risk jamming the card (with paper and so on) in the slot and causing even more damage. And if your device uses a “lock” or “swing” slot you may end up forcing the mechanism, and then you won't be able to use it anymore.
If you have recently updated your device, try this
It is not common, but it happened to me: if your smartphone stopped recognizing the card exactly after a system update, something may have gone wrong during the process and causing the problem. In this case, in addition to the previous suggestions, try performing a factory reset.
The idea is to remove any leftover configuration or parameters from a previous version of the system that is detrimental to operation. In this process all data from your device will be deleted and it will behave as if it just came out of the box with all settings reset to their default values. The difference is that it will continue to run the new version of the operating system.
To restore, go to Configure / Backup and Restore / Original Configuration. Click Reset phone and wait for the process to complete. But first backup all important data and applications on your device as they will be deleted.
Here you will find a little help:
- Best Android Backup Apps - How to Backup Android 
- How to format your phone [Android hard reset]
If all of this has not worked, then you have to admit him to a service center. Get your smartphone ready, get the bill and a dose of patience. Hope your device works soon.
Have you ever had a similar problem? What did you do to solve? Share your experience in the comments below.