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Overview & Common Error Messages

If your Xiaomi or Redmi smartphone suddenly displays “No Service”, “SIM Not Detected”, or “Emergency Calls Only”, it usually points to software glitches following MIUI/HyperOS updates, improper radio band settings, or corrupted network configurations.

Common Error Signals:

  • No Service

  • Emergency Calls Only

  • SIM Card Not Detected / Invalid SIM

  • SIM Card Failed

Step-by-Step Troubleshooting Methods

  • Method 1: Reset Mobile Radio Power via Diagnostic Code

    1. Open the Phone Dialer.

    2. Dial *#*#4636#*#* to launch the hidden Testing Menu.

    3. Select Phone Information 1 or Phone Information 2 (depending on which SIM slot has the issue).

    4. Locate Mobile Radio Power. If it is turned ON, toggle it OFF.

    5. Wait 10 seconds, turn Mobile Radio Power back ON, and exit the menu.

  • Method 2: Change Preferred Network Type

    1. Go to Settings > SIM Cards & Mobile Networks.

    2. Select the affected SIM card.

    3. Tap Preferred Network Type.

    4. Switch from Prefer 5G/LTE to 3G, or vice versa, to force the device to re-register on the network.

    5. Restart the device.

  • Method 3: Quick Network Refresh (Airplane Mode Toggle)

    1. Swipe down the Quick Settings panel.

    2. Enable Airplane Mode and wait 10–15 seconds.

    3. Disable Airplane Mode to force the modem to reconnect to local cell towers.

  • Method 4: Reset Network Settings (Advanced Fix)

    1. Open Settings > Connection & Sharing.

    2. Tap Reset Wi-Fi, Mobile Networks & Bluetooth.

    3. Select the affected SIM card at the bottom.

    4. Tap Reset Settings and confirm your security PIN/password.

  • Hardware & Card Checks:

    1. Power off the phone and remove the SIM tray using an ejector tool.

    2. Clean the golden contact points of the SIM card with a dry microfiber cloth.

    3. Reinsert the card into SIM Slot 2 (if available) or test it inside another smartphone to confirm if the SIM card itself is physically damaged or deactivated by the carrier.

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