Have you inserted a SIM card into your smartphone, but instead of the usual network icons, the screen displays the message "No SIM card", "SIM card not found" or "Insert SIM card"? The problem is familiar to millions of Android users - from budget Redmi to flagship Samsung Galaxy. In 80% of cases, the malfunction can be fixed on your own without contacting a service center. But to do this, you need to accurately determine the source of the failure: either the fault is SIM card slot, or phone firmware, or the operator card itself.

In this article we will analyze all possible reasons - from banal contamination of contacts to hardware failures of the motherboardand also give clear diagnostic instructions. You'll learn how to distinguish a software glitch from a physical malfunction, which Android settings to check first, and when it's really time to take your phone in for repair. For convenience, we have compiled a table of symptoms and solutions, and also added interactive checklists - just follow the steps.

Spoiler: if your Xiaomi, Honor or Realme stopped seeing the SIM card after a crash or update - these are two fundamentally different scenarios. In the first case, the contacts most likely came loose, in the second, the modem configuration was lost. And the solutions for them are radically different.

1. Checking the SIM card: the simplest steps before diagnosing the phone

Before delving into the smartphone settings, make sure that the problem is not in the SIM card itself. This stage takes 2 minutes, but allows you to exclude 30% of possible causes.

  • 🔄 Restart your phone. It’s trivial, but in 15% of cases it helps - especially if a failure occurred after installing an application or update.
  • 📱 Check the card in another phone. Insert it into a working device (for example, a friend's or an old spare). If there is no network there either, the problem is in the SIM card, not in your smartphone.
  • 🛠️ Clean the contacts. Take an eraser (or microfiber moistened with alcohol) and gently wipe the gold contacts on the SIM card. Grease marks or oxidation may interfere with the connection.
  • ✂️ Check the card size. If you use an adapter for nano-SIM in the slot micro-SIM, make sure that the card fits tightly and does not loosen.

If the SIM card works in another phone, but is not detected in yours, go to the next section. If it is inactive everywhere, most likely:

  • 📵 Card blocked by the operator (for example, due to a late payment or suspicious activity).
  • 🔌 Damaged chip (visually check for cracks or darkening).
  • ⏳ Expired expiration date (for some operators, the SIM is deactivated after 6-12 months without use).
⚠️ Attention: If you recently changed your tariff or operator, make sure your SIM card is activated. For some providers (for example Tele2 or Yota) activation takes up to 24 hours.
📊 Your phone stopped seeing the SIM card after
Falls/impact
Firmware updates
Change of operator
On its own
I don’t know

2. Diagnostics of the SIM card slot: mechanical and contact problems

If the SIM card is working, but the phone does not see it, the next “weak link” is SIM card slot (aka SIM-tray). There are three possible types of faults here:

  1. Physical damage (crack in the board, bent contacts).
  2. Contamination or oxidation contacts.
  3. Loose fit (the card is not fixed, dangles).

How to check:

☑️ SIM card slot diagnostics

Done: 0 / 4

🔍 Visual inspection:

  • 🕳️ Take out the SIM card tray and shine a flashlight into the slot. If dust, fibers or corrosion are visible inside, this is a potential cause.
  • 🔌 Pay attention to moving contacts (metal “antennae”). They must be smooth, not bent or oxidized.
  • 📏 Make sure that the tray is inserted all the way without any play. If it dangles, the latch may be broken.

🛠️ Cleaning contacts:

Use isopropyl alcohol (90%+) and a cotton swab. Gently wipe the contacts inside the slot and on the SIM card itself. Do not use water or acetone! After cleaning, allow 5 minutes to dry.

⚠️ Attention: If the contacts are inside the slot are bent, do not try to straighten them yourself - you risk tearing them off the board. In this case, contact the service.

🔧 Test with another SIM card:

If you have a spare SIM card (even an inactive one), insert it into the slot. If the phone “sees” it, the problem was in the first card. If not, there is a malfunction in the slot or the phone.

What to do if the SIM card tray is broken?

If the tray lock has broken off, you can temporarily secure the SIM card with tape (carefully, without covering the contacts) or use a tray from another phone (if it is the right size). But this is a temporary solution - for permanent use you will need to replace the slot in the service.

3. Software failures: when the firmware or settings are to blame

If the SIM card and slot are working, but the phone still does not see the network, the problem lies in software. This could be:

  • 📱 Malfunction modem (responsible for communication).
  • 🔄 Incorrect network settings (for example, manual selection of an operator).
  • 🐛 Bug after Android update.
  • 🚫 IMEI blocking (if the phone is blacklisted).

Let's start with the simplest thing - checking the settings.

Checking network settings

Go to Settings → Connections → Mobile network (path may vary depending on model). Make sure that: Settings → Connections → Mobile network data-i="141">4G/3G/2G (auto)

  • 📶 Mobile data included.
  • 🔄 Network mode installed on 4G/3G/2G (auto).
  • 🏢 Operator selected in mode Automatic (if manually, try resetting).
  • 📡 Roaming enabled (if you are abroad).

If the settings are correct, but there is still no network, try reset the network settings:

  1. Open Settings → System → Reset.
  2. Select Reset network settings (or Reset Wi-Fi, mobile network and Bluetooth).
  3. Confirm the action and restart the phone.
⚠️ Attention: After To reset the network, you will have to re-enter Wi-Fi passwords and pair Bluetooth devices.

Re-registering in the operator's network

Sometimes the phone freezes while searching for a network. To force a reconnection:

  1. Turn on airplane mode for 30 seconds, then turn off.
  2. If that doesn’t help, manually select the operator:
    1. Go to Settings → Mobile network → Network operators.
    2. Disconnect Automatic and wait for the search for available networks.
    3. Select your operator manually.

Reset APN

APN (Access Point Name) - these are the mobile data access settings. If they are lost, the phone may not see the network. To reset:

  1. Open Settings → Mobile network → Access points (APN).
  2. Click on the three dots in the upper right corner and select Reset to default.
  3. Restart your phone.

If after the reset the APNs do not appear automatically, you can add them manually (the settings are usually available on your operator's website).

💡

If after updating Android the phone no longer sees the SIM card, try rolling back to the previous firmware version. To do this, find the official firmware for your model on the manufacturer's website (for example, Xiaomi or Samsung) and flash the phone via Fastboot or Recovery.

4. Hardware failures: when you can’t do without a service

If all software methods have been tried, but the phone still does not see the SIM card, most likely the problem is hardware. Here are the most common breakdowns:

Symptom Probable cause Solution
The phone does not see any SIM card, but Wi-Fi and Bluetooth work The modem is faulty Modem is detected, but there is no network (no operator icon) or its power supply is faulty Diagnostics in the service, replacing the modem or soldering contacts
The SIM card is detected, but there is no network (no operator icon) Damaged antenna or its cable Replacing the antenna module
The phone sees the SIM card only after reboot Problems with IMEI memory or modem firmware Flashing or restoring IMEI
The SIM card is detected, but does not catch the network in some places Damaged RF path (signal amplifier) Diagnostics on special equipment

🔧 How to diagnose a hardware failure:

  1. Check IMEI: Dial *#06#. If, instead of a 15-digit code, Null or Unknown is displayed, the IMEI has gone wrong (this can be solved by flashing or restoring through the engineering menu).
  2. Look at the indicators: If the phone does not respond to the inserted SIM card at all (there is not even an attempt network search), the problem may be on SIM card controller on the motherboard.
  3. Check after the fall: If the phone has been dropped or gotten wet, there is a high probability of microcracks on the board. In this case, only diagnostics under a microscope.

💡 Repair cost:

  • 🔧 Replacing the SIM card slot: 500–1500 ₽.
  • 📡 Replacement antenna module: 1000–3000 ₽.
  • 🔌 Modem repair/replacement: 2000–8000 ₽ (depending on the model).
  • 🔬 Diagnostics of microcracks: from 1000 ₽.
⚠️ Attention: If your phone is under warranty, do not open it yourself - this will void the warranty. Contact the official service center.
💡

If the phone stops seeing the SIM card after being dropped, wet or overheated, there is a 90% chance that this is a hardware failure. Software methods will not help here - diagnostics in the service are required.

5. Problems with IMEI: why the phone does not connect to the network even with a working SIM card

IMEI (International Mobile Equipment Identity) - this is a unique identifier for your phone. If it is knocked down or blocked, the phone will not be able to connect to the operator’s network, even if the SIM card is working.

🔍 How to check IMEI:

  1. Dial on the keyboard *#06#.
  2. If instead of 15 digits you see Null, Unknown or an empty field - IMEI lost.
  3. Check whether the IMEI matches what is indicated on the box or under the battery (if the phone is collapsible).

🛠️ Reasons for losing IMEI:

  • 📱 Incorrect firmware (especially on MediaTekphones).
  • 🔄 Failure after resetting to factory settings.
  • 🛠️ Inept intervention in the engineering menu.
  • 🚫 Blocking by the operator (if the phone is blacklisted).

🔧 How to restore IMEI:

The method depends on the phone processor:

  • For Qualcomm: Use the engineering menu (##4636##) or utilities like QPST.
  • For MediaTek: Need apps MTK Engineering Mode or Maui META.
  • For Samsung Exynos: Requires Odinh and original firmware.
⚠️ Attention: IMEI restoration on some models (for example, Xiaomi with a locked bootloader) can lead to briku (total inoperability) of the phone. If you are not sure, contact the service.

📝 How to avoid losing IMEI:

  • 🔄 Do not reset settings via Fastboot without backup.
  • 📱 Do not install custom firmware without checking compatibility.
  • 🛠️ Do not change the settings in the engineering menu if you do not know their meaning.

6. Features of different brands: Samsung, Xiaomi, Honor and others

Each manufacturer has its own “sores”, due to which the phone may not see the SIM card. Let's look at the most common ones.

Samsung Galaxy (including A-series and S-series)

  • 🔧 Problem: After updating to One UI 5/6 the phone stops seeing the SIM card.
  • 🛠️ Solution: Reset the network settings or roll back to the previous firmware version via Smart Switch.
  • ⚠️ Common reason: Failure eSIM (if the phone supports two SIM cards). Try disabling eSIM in the settings.

Xiaomi (Redmi, POCO)

  • 🔧 Problem: The phone does not see the second SIM card (especially in models with a hybrid slot).
  • 🛠️ Solution: Check whether the slot conflicts with the memory card. Insert the SIM card into the first slot.
  • ⚠️ helps. Common reason: Bug in the firmware MIUI. Resetting through Fastboot with cleaning modemst1 and modemst2.

Honor and Huawei

  • 🔧 Problem: After updating to EMUI 12+ or Magic UI the network disappears.
  • 🛠️ Solution: Turn on Safe Mode (hold down the power button → “Safe Mode”). If the SIM card works in it, a third-party application is to blame.
  • ⚠️ Common reason: Conflict with Google Mobile Services (if the phone does not have Google services). Try installing GMS via LZPlay.

Realme, Oppo, Vivo

  • 🔧 Problem: The phone sees the SIM card, but does not pick up the network (no operator icon).
  • 🛠️ Solution: Go in Settings → SIM card and mobile data → Access point name (APN) and reset the settings.
  • ⚠️ A common reason helps: Bug in ColorOS. Flashing via Oppo Realme Flash Tool.

📌 General advice: If the problem appeared after updating the firmware, check the forums (for example, 4PDA or XDA-Developers) - perhaps this is a massive bug, and there is already a patch.

7. What to do if nothing helps: extreme measures

If you have tried all the methods, but the phone still does not see the SIM card, there are radical methods left:

  • 🔄 Reset to factory settings (will delete all data!):
    1. Make a backup important data.
    2. Go to Settings → System → Reset → Reset all data.
    3. After resetting, do not restore data from the backup immediately - check if the SIM card works.
  • 📱 Flashing phone:
    1. Download the official firmware for your model from the manufacturer's website.
    2. Flash the phone via Fastboot or Recovery (instructions are available at 4PDA).
    3. For Samsung use Odinto Xiaomi — Mi Flash Tool.
  • 🛠️ Contact service:
    1. If the phone is under warranty, take it to an official service center.
    2. If there is no guarantee, look for a proven service with good reviews (for example, on Yandex.Maps or 2GIS).
    3. Check the cost of diagnostics in advance - in some services it is free.
⚠️ Attention: If you decide to flash the phone yourself, be prepared for the risk of “bricking” (complete inoperability). Always check the compatibility of the firmware with your model!

💡 Advice before visiting the service:

  • 📝 Write down all the symptoms (when the problem appeared, what have you already tried).
  • 🔧 Check if the service has experience working with your model.
  • 💰 Ask about the warranty for repairs (good services provide from 3 months).

8. Prevention: how to avoid problems with the SIM card in the future

To avoid encountering the “phone does not see the SIM card” problem again, follow these recommendations: