When the mobile does not recognize the SIM card, we face a situation that can be frustrating, as we are left without communication and limited in the use of our device. Fortunately, most of these problems can be solved, and there are precise methods and steps to identify the cause and restore the phone's functionality. From software issues, configuration errors, and dirt, to damaged cards or incompatible bands, We will thoroughly address all possible variables and solutions. so that your phone recognizes the SIM card again and you can take advantage of all the functions of your device.
Why doesn't my phone recognize the SIM card?: Possible causes
Before going directly into the solutions, it is essential Understanding why a mobile phone may stop recognizing a SIM cardThere are several causes, and identifying them will save you time and help you find the most effective solution:
- Incorrect placement: The SIM card is not properly inserted into the corresponding slot or tray, which is common in models with shared slots with microSD.
- Damaged, bent, or old SIM card: The passage of time, handling, humidity or falls can physically deteriorate it or demagnetize the chip.
- Dirt on the contacts or the reader: Dust, lint, or grease residues hinder the metallic contact necessary for the SIM to work.
- Software problems after updates: A bug in the operating system, corrupted SIM management applications, or update errors could be the cause.
- Mobile network configuration error: Selecting an incompatible band, having airplane mode active, or disabling mobile data may prevent SIM recognition.
- SIM reader failure: Damage to the pins, misalignments, or even damaged internal components after falls.
- Card blocked (PIN or PUK): If an incorrect code is entered repeatedly, the SIM card will be blocked until the correct PUK is entered.
- Lack of coverage, operator interruption or cut line: If the line has been disconnected due to non-payment, incomplete portability, or a failure in the operator's network.
- Device not unlocked (especially if you try to use a SIM from another operator in a mobile phone locked to a specific company).
- Damaged SIM tray: If it is deformed, broken, or does not fit perfectly into the corresponding slot, the mobile phone will not be able to establish contact.
Identifying the specific cause will allow you to rule out solutions that won't work and focus on the most appropriate procedure.
First steps to diagnose the problem
Diagnosis is key to efficiently resolve the problem. Here are the first steps to determine if the problem is with the SIM, the phone, the settings, or the network:
- Check the line with your operator: Access the app, customer area, or check your email to confirm that the line is still active and current. You can also rule out temporary service interruptions by checking social media or DownDetector.
- Check the coverage and service status in your area: Consult with other people from your network or try moving to places with a stronger signal. In rural areas or buildings with poor reception, the SIM may not register.
- Check the SIM status from the phone menu: In the Settings app, look for “SIM Status” to see if it detects it correctly (some menus display information about the inserted SIMs, ideal for Dual SIM phones).
- Try the SIM in another phone and vice versa: Insert your SIM into another working device and a different SIM into your phone. This way, you'll know if the problem is with the card or the device. Remember that if your phone is carrier-locked, it will only recognize SIMs from that company.
- Turn airplane mode off and on: It is a quick method to force the system to reconnect to the network.
Basic solutions: restart, remove and insert the SIM correctly
The simplest solutions are often the most effective, especially if the fault is a temporary software error or a faulty contact:
- Restart the mobile from the Quick Panel or by holding down the power button. This can resolve residual system conflicts and is a common solution to one-time errors.
- Remove the SIM card: Turn off your phone before removing the SIM to avoid electrical damage. Use the removal tool (or a paper clip) and inspect the card and tray. If the SIM is not inserted correctly, you may notice it sticking out, moving, or being inverted.
- Reinsert the SIM: Gently clean the gold contacts with a dry, lint-free cloth (microfiber is best). Make sure the tray and slot are clean and insert the SIM firmly, without forcing it. If the tray is damaged or deformed, replace it.
- Additional cleaning of the reader and tray: If you find dirt in the slot, you can use a blowtorch or low-pressure compressed air (do not use sharp objects like pins or knives, which can damage the reader's pins). You can also clean the tray with a cotton swab lightly moistened with isopropyl alcohol, letting it dry before reinserting.
Checking if the SIM fits perfectly is essentialThis ensures proper contact with the reader pins. If the SIM card is loose, try tightening it slightly or placing a folded piece of paper over the area opposite the contacts to improve the fit.
Checking the SIM and Tray: Avoiding Common Mistakes
A very common mistake is Inserting the SIM into the wrong tray, placing the tray upside down, or using the microSD slot instead of the SIM card. Consult the manufacturer's instructions if you have any questions; never force the tray, as this may damage it or bend the internal contacts.
On dual-SIM phones, make sure the system is trying to read the SIM in the correct slot (some phones allow you to disable one of the SIMs from the settings).
Complete cleaning of the SIM card and reader
Dirt, dust, or grease are some of the most common causes of SIM card reading errors. Here's the complete and safe process for cleaning the components:
- Turn off your phone and carefully remove the SIM card and tray.
- With a microfiber cloth (never paper or tissues), clean the gold contacts of the SIM without rubbing excessively.
- If there are stubborn stains, use a swab slightly moistened with isopropyl alcohol and let it dry before reinserting it.
- Clean the tray with the same cloth or swab.
- Blow out the slot or use compressed air/air bulb being careful not to damage the internal pins.
- Avoid using water or corrosive liquidsNever scratch the contacts with metal objects.
- Reassemble everything and check that it works.
This procedure eliminates most problems caused by accumulated dirt. If the problem persists, continue with the following checks.
Test the SIM on other devices and vice versa
This step is essential for isolate the source of the faultInsert your SIM card into another compatible, unlocked phone. If the SIM card works in another phone, the problem lies with the reader or your device's software. If it's not recognized either, it's a clear sign that the card is damaged or inactive.
It's also recommended to insert another SIM card (preferably from the same carrier in case the phone isn't unlocked) into your phone. If this other card works correctly, confirm that the original is defective or deactivated. For more details on detection and manipulation, please consult How to know the ICC without taking out the card.
Request a SIM Duplicate to your operator if after all the tests the original card still does not work in several phones.
Advanced software and configuration solutions
Reset network settings
In some cases, the The device's network settings may be corrupted or outdated, which prevents the SIM from registering properly with the mobile network. Resetting network settings restores the default settings without erasing your personal files.
- On Android: Go to Settings > System > Recovery options > Reset mobile network settings.
- On iPhone: Settings > General > Transfer or Restore > Restore > Reset Network Options.
This will clear your Wi-Fi, Bluetooth, and APN settings, but may also fix connection and SIM card detection issues.
Turn airplane mode off and on
El Airplane mode cuts off all connectivity to the device, which can help resolve network conflicts. Activate it from the quick panel (airplane icon), wait a few seconds or a minute, and deactivate it. After this process, the phone will attempt to reconnect to the network and register the SIM.
Update the operating system
An outdated system or one with known bugs can interfere with SIM card reading and management:
- Go to Settings > About phone > System update.
- Install pending updates, restart your phone, and check if the error is resolved.
In some cases, temporary incompatibilities may occur after a recent update. Consult the manufacturer's support if the issue is related to a software update.
Clear the system cache
The Corrupt temporary files can cause SIM recognition failuresOn many Android phones, you can clear the cache by accessing the recovery menu:
- Turn off the phone.
- Press the volume up button and the power button at the same time.
- Wait until you feel the vibration and enter the recovery menu.
- Select “Clear cache”.
- Reboot your phone using the “Reboot” option.
Correct APN and mobile network configuration
El APN (Access Point Name) It is the access point that allows the SIM to connect to the mobile data network. If it is not configured correctly, the SIM may be recognized but you will not have Internet access or you may even receive a SIM not detected error. To do this, see the instructions for configure the APN correctly.
- Go to Settings > Mobile Networks > APN or Access Point.
- Manually add the parameters provided by your operator (name, username, password, etc.).
- Save and select the created APN as active.
If you have any questions, check your carrier's support page, where they usually provide this information.
Change network type and selection mode
If your phone is set to connect to a band not supported by your carrier, it may prevent SIM registration:
- On Android: Settings > Connections > Mobile networks > Network mode (choose 4G/3G/2G auto or the most compatible option).
- On iPhone: Settings > Cellular > Options > Voice & Data (choose the most appropriate band).
Restore your phone to factory settings (Extreme Solution)
If after trying all of the above, your phone still doesn't recognize your SIM card, and you've verified that the SIM card works in other devices, your phone's software may be corrupted or there's a deep error. You can also check How to fix SIM card lock to check for possible internal errors. Always make a backup before performing a hard reset, as it will delete all your data.
- Settings > System > Reset > Factory data reset.
- Follow the instructions and start the restoration.
On iPhone: Settings > General > Transfer or Reset iPhone > Erase All Content and Settings. Reinstall the SIM and check if it's recognized after the system reinstallation.
Advanced Checks: Hidden Menu, Diagnostics, and Hardware
Some brands include hidden diagnostic menus accessible by entering codes from the calling app. This allows you to check the SIM card reader's status and other technical parameters:
- Samsung: * # 0011 #
- Xiaomi: ##6484##
- iPhone: 3001#12345#
- Realme: *#800#
- Huawei: ##2846579##
In these menus, you can check if the device is receiving a signal, if the SIM card reader is working, or if there are any errors in the network protocols. For more information, see How to recover the PUK code if you lost your SIM card.
What should you do if your SIM is new or you just ported it?
If the SIM has just been delivered after a portability or registration, check that has been successfully activated. Sometimes there's a wait time for the line to fully activate. If the error persists after several hours, contact your carrier's support. You can also check to make sure your system settings are correct.
If your SIM card has been blocked due to entering the wrong PIN repeatedly, enter the PUK code, which is usually printed on the plastic card holder that came with your SIM card. If you don't have it, call your network provider to request it.
Operator, coverage, or service interruption issues
If after checking all the hardware, the SIM still does not work, but you do not have coverage in the area or the error is shared by other users of your operator, it is likely that there is a network failure or a service interruption (due to maintenance, incidents, or non-payments). To resolve these issues, you can also consult .
You can check this in your operator's customer area or on their incident platforms.
Special cases: eSIM and Dual SIM phones
The eSIM Virtual SIM cards are becoming more common. If your phone uses eSIM, make sure the system is properly configured and that activation is successful. For details, see . Also, for dual-SIM phones, verify that both cards are activated and configured correctly in the system settings.
Extreme case: reader failure or hardware problem
If the problem persists after trying the SIM in other phones, performing wipes, restoring settings, checking settings, hidden menus, updating the system and resetting the phone, there is likely a hardware failure SIM reader. This can happen after impacts, drops, rust, moisture, or wear on the contact pins. For more details, see .
In this case, go to an official technical serviceRepair may be included if the device is still under warranty and the failure is not due to misuse. Consult an authorized center for a detailed evaluation.
Solutions for damaged SIM cards, duplicates, and data recovery
If after all the tests it is determined that the SIM is bent, scratched, burned, or damaged over time, request a duplicate from your operator. Remember that data stored on the SIM (contacts, old SMS) They are lost when you create a duplicate, so we recommend transferring them to your Google account or mobile storage first if they can be accessed from another device. To learn how to transfer contacts, visit carry the transport card on your Android phone.
Frequently asked questions and common doubts
- Why doesn't my phone recognize the SIM after updating? It could be a temporary software glitch. Restart, clear your cache, or wait for a patch. For more help, see .
- Can a fall damage the SIM reader? Yes, impacts can dislodge pins, bend the tray, or even break internal components.
- What do I do if my phone only recognizes the SIM sometimes and disconnects? There's probably poor contact, dirt, or damage to the tray. Clean it and check the fit.
- Does age or SIM type matter? Old SIM cards can fail due to wear and tear, and new ones must be properly activated.
- What happens if I change operators? Make sure your phone is unlocked and compatible with the new carrier's bands and frequencies.
If you've gotten this far and your phone still doesn't recognize your SIM card, don't despair. Follow the step-by-step process or call a technician. However, most users can resolve the issue by following these instructions.
