How to Repair IMEI on Qualcomm and MediaTek Devices: Complete Guide 2024

IMEI (International Mobile Equipment Identity) is the unique 15-digit number that identifies your smartphone on mobile networks. When this number becomes null, corrupted, or invalid, your device loses network connectivity, showing "No Service" or "Emergency Calls Only." This comprehensive guide will teach you how to repair IMEI on both Qualcomm and MediaTek Android devices using professional tools and proven methods.

What is IMEI and Why Does It Get Corrupted?

IMEI (International Mobile Equipment Identity) is a unique 15-digit identifier assigned to every mobile device with cellular capabilities. Think of it as your phone's fingerprint - no two devices should have the same IMEI number. This number is crucial for:

• Network Authentication - Mobile carriers use IMEI to identify and authorize devices on their networks
• Device Tracking - IMEI helps track stolen devices and block them from networks
• Warranty Claims - Manufacturers use IMEI to verify device authenticity and warranty status
• Regulatory Compliance - IMEI ensures devices meet regional telecommunications standards

Common IMEI Problems

IMEI corruption manifests in several ways:

• Null IMEI - Shows as 000000000000000 or blank
• Invalid IMEI - Shows incorrect or non-standard numbers
• Missing IMEI - One or both IMEI slots show "Unknown" (dual SIM devices)
• Baseband Unknown - Network firmware corruption affecting IMEI storage
• No Service - Device can't register on any mobile network

Common Causes of IMEI Corruption

1. Failed Firmware Flash - Interrupted firmware updates or incorrect ROM installation
2. Partition Damage - Corruption of EFS (Qualcomm) or NVRAM (MediaTek) partitions
3. Water Damage - Physical damage affecting modem components
4. Factory Reset Gone Wrong - Sometimes wipes critical system partitions
5. Custom ROM Installation - Improper ROM flashing without EFS/NVRAM backup
6. Hardware Repair - Motherboard replacement or chip-level repairs
7. Malware Attack - Rare but possible with compromised firmware

Required Tools and Downloads

For Qualcomm Devices

For MediaTek Devices

Method 1: Repair IMEI on Qualcomm Devices

Qualcomm-powered smartphones (Snapdragon processors) store IMEI information in the EFS (Embedded File System) partition. This partition contains critical network calibration data including IMEI, network unlock codes, and carrier provisioning information.

Prerequisites for Qualcomm IMEI Repair

• ✅ Qualcomm Snapdragon device (verify chipset)
• ✅ Windows PC (Windows 7 or newer)
• ✅ USB cable (original or high-quality)
• ✅ Device battery charged to at least 50%
• ✅ Original IMEI number (check device box, invoice, or label under battery)
• ✅ Qualcomm drivers installed
• ✅ QPST or QFIL tool installed
• ✅ Device in diagnostic/EDL mode

Step 1: Backup QCN File (Important!)

QCN (Qualcomm Calibration Network) file contains your device's network calibration data. Always backup before IMEI repair!

1. Enable USB Debugging on your device
2. Connect device to PC via USB
3. Open QPST Configuration from Start Menu
4. Click "Ports" tab → Verify device is detected
5. Open RF NV Manager from QPST tools
6. Click "Read from Phone" button
7. Save QCN file with device model name (e.g., `galaxy_a10_qcn_backup.qcn`)
8. Store backup safely on external drive

Step 2: Boot Device into Diagnostic Mode

Qualcomm devices need to be in diagnostic mode for IMEI writing:

Method A: Dialer Code (Easiest)

1. Open Phone Dialer app
2. Dial: *#*#3646633#*#* or *#*#7378423#*#*
3. Select "Service Menu" → "USB Settings"
4. Enable "Diagnostic Mode" or "DM+ADB+Modem"
5. Connect USB → Check Device Manager for Qualcomm HS-USB port

Method B: ADB Command

1. Enable USB Debugging in Developer Options
2. Connect device to PC
3. Open Command Prompt in ADB folder
4. Type: adb devices (verify device detected)
5. Type: adb reboot ftm (boots to field test mode)

Method C: EDL Mode (Advanced)

1. Power off device completely
2. Hold Volume+ and Volume- simultaneously
3. Connect USB cable while holding buttons
4. Device enters EDL mode (blank screen)
5. Check Device Manager for Qualcomm HS-USB QDLoader 9008

Step 3: Write IMEI Using QPST

Using EFS Explorer Method:

1. Open EFS Explorer from QPST tools
2. Device should auto-detect in diagnostic mode
3. Navigate to folder structure:
   • /nv/item_files/modem/mmode/ue_usage_setting
4. Locate IMEI configuration files (usually XML or binary)
5. Right-click → Edit or Replace with correct IMEI
6. For dual SIM:
   • IMEI1 in /nv/item_files/modem/mmode/imei_1
   • IMEI2 in /nv/item_files/modem/mmode/imei_2
7. Save changes and reboot device

Using DFS CDMA Tool (Professional Method):

1. Download and install DFS CDMA Tool
2. Connect device in diagnostic mode
3. Open DFS → Select device port from dropdown
4. Navigate to "Connectivity" or "IMEI" tab
5. Enter original IMEI number (without spaces or dashes)
6. For dual SIM devices:
   • IMEI1: Primary SIM slot
   • IMEI2: Secondary SIM slot (usually IMEI1 + 1)
7. Click "Write IMEI" button
8. Wait for success confirmation
9. Reboot device

Step 4: Restore QCN Backup

1. After IMEI writing, restore QCN backup
2. Open RF NV Manager
3. Click "Write to Phone"
4. Select your QCN backup file
5. Wait for write process to complete
6. Reboot device

Step 5: Verify IMEI Repair

1. Boot device normally
2. Dial *#06# in phone dialer
3. IMEI should display correctly
4. Check Settings → About Phone → IMEI
5. Verify both IMEI1 and IMEI2 (dual SIM)
6. Insert SIM card and test network connectivity
7. Check signal strength and data connectivity

Method 2: Repair IMEI on MediaTek Devices

MediaTek devices store IMEI in the NVRAM (Non-Volatile RAM) partition. MediaTek IMEI repair is generally easier than Qualcomm and offers multiple methods including built-in engineering mode.

Prerequisites for MediaTek IMEI Repair

• ✅ MediaTek chipset device (MT6xxx, Helio, Dimensity series)
• ✅ Original IMEI number (from box or device label)
• ✅ MediaTek USB VCOM drivers installed
• ✅ Device charged to 50%+ battery
• ✅ USB cable (quality matters!)
• ✅ NVRAM backup (highly recommended)

Method A: Using MTK Engineering Mode (No PC Required)

This is the easiest method and works on most MediaTek devices running Android 5.0 to Android 12.

Step 1: Access Engineering Mode

1. Open Phone Dialer app
2. Dial one of these codes:
   • *#*#3646633#*#* (Most common)
   • *#*#4636#*#* (Alternative)
   • *#*#54298#*#* (Some devices)
3. Engineering Mode menu will appear automatically
4. If codes don't work, download "MTK Engineering Mode" app from Play Store

Step 2: Navigate to CDS Information

1. In Engineering Mode, select "Connectivity"
2. Select "CDS Information"
3. Select "Radio Information"
4. You'll see "Phone 1" section

Step 3: Write IMEI via AT Commands

1. Scroll down to the text box that says "AT Command"
2. Type the following command carefully:

For IMEI1 (Primary SIM):

AT+EGMR=1,7,"YOUR_IMEI_HERE"

Example:

AT+EGMR=1,7,"352094087456123"

For IMEI2 (Secondary SIM - Dual SIM devices):

AT+EGMR=1,10,"YOUR_IMEI2_HERE"

3. Replace "YOUR_IMEI_HERE" with your actual 15-digit IMEI
4. Click "Send AT Command" button
5. You should see response: AT+EGMR: FLAG = 0 (success)
6. If error occurs, double-check IMEI format (15 digits, no spaces)
7. Repeat for IMEI2 if dual SIM device
8. Reboot device

Step 4: Verify IMEI

1. After reboot, dial *#06#
2. IMEI should now display correctly
3. Insert SIM and test network

Method B: Using Chamelephon Tool (PC Method)

Chamelephon is a popular free tool for MediaTek IMEI repair that works even when engineering mode is disabled.

Step 1: Prepare Device

1. Enable USB Debugging in Developer Options
2. Install MediaTek USB VCOM drivers on PC
3. Download and extract Chamelephon Tool
4. Connect device to PC via USB

Step 2: Run Chamelephon

1. Launch Chamelephon.exe as Administrator
2. Tool will auto-detect your MediaTek device
3. Device info will display (model, chipset, IMEI status)

Step 3: Write IMEI

1. In the main window, you'll see two IMEI fields
2. IMEI 1: Enter primary SIM IMEI (15 digits)
3. IMEI 2: Enter secondary SIM IMEI (dual SIM only)
4. Click "Apply" or "Write IMEI" button
5. Wait for confirmation message
6. Tool will show "IMEI written successfully"
7. Disconnect device and reboot

Method C: Using SN Write Tool (Official Method)

SN Write Tool is MediaTek's official utility for writing serial numbers and IMEI during manufacturing. It's the most reliable method.

Step 1: Backup NVRAM

1. Open SP Flash Tool
2. Click "Readback" tab
3. Add readback item → Select NVRAM partition
4. Save as nvram_backup.bin
5. This backup is crucial for data recovery

Step 2: Prepare SN Write Tool

1. Extract SN Write Tool package
2. Locate SN.txt file
3. Open in Notepad
4. Format: SN: SERIALNUMBER IMEI1 IMEI2 BT_MAC WIFI_MAC
5. Example: SN: 123456789ABC 352094087456123 352094087456124 00:11:22:33:44:55 AA:BB:CC:DD:EE:FF
6. Save file

Step 3: Write IMEI

1. Power off device completely
2. Open SN Write Tool as Administrator
3. Load SN.txt file
4. Load appropriate Database file (AuthAV.xml) for your chipset
5. Click "Start" button
6. Connect device via USB (hold Volume Down or no buttons)
7. Tool will detect device and write IMEI automatically
8. Wait for green "PASS" message
9. Disconnect and boot device

Method D: Using MTK Droid Tools (All-in-One Solution)

1. Download and install MTK Droid Tools
2. Enable USB Debugging on device
3. Connect device to PC
4. Open MTK Droid Tools → Device will auto-detect
5. Go to "IMEI & NVRAM" tab
6. Click "Read NVRAM" to backup (important!)
7. Enter new IMEI in IMEI1 and IMEI2 fields
8. Click "Write IMEI" button
9. Wait for success message
10. Reboot device

IMEI Repair for Specific Brands

Samsung Devices

Samsung uses both Qualcomm and Exynos chipsets. IMEI repair depends on your model:

• Qualcomm Samsung (US models): Use QPST/QFIL methods above
• Exynos Samsung (International): Requires specialized tools like Z3X or Octoplus
• Important: Samsung Knox may block IMEI writing on newer devices
• Download Samsung firmware for ROM repair

Xiaomi/Redmi Devices

• All Xiaomi devices use Qualcomm Snapdragon processors
• IMEI stored in EFS partition (similar to other Qualcomm devices)
• Easiest method: QFIL + DFS CDMA Tool
• Alternative: Mi Flash Tool + QCN restore
• Download Xiaomi fastboot ROMs

Oppo & Vivo Devices

• Mostly use MediaTek chipsets (Helio/Dimensity series)
• Some flagship models use Qualcomm Snapdragon
• Engineering Mode AT commands work well on most models
• Chamelephon tool is highly effective
• Download Oppo firmware or Vivo firmware

Realme Devices

• Mix of MediaTek and Qualcomm chipsets
• MediaTek models: Use MTK Engineering Mode
• Qualcomm models: Use QPST/QFIL methods
• Most reliable: SN Write Tool for MTK models
• Download Realme firmware

Tecno & Infinix Devices

• Exclusively MediaTek chipsets (all models)
• Engineering Mode codes work on 99% of devices
• AT+EGMR commands are most effective
• MTK Droid Tools also works well
• Download Tecno firmware or Infinix firmware

Advanced Troubleshooting

Problem: IMEI Changes Back After Reboot

Causes:

• NVRAM or EFS partition corruption
• Security software overwriting IMEI
• Incorrect backup restoration

Solutions:

1. For Qualcomm: Restore QCN backup after IMEI write
2. For MediaTek: Backup NVRAM before writing IMEI
3. Flash stock firmware to repair partitions
4. Write IMEI again after fresh ROM flash
5. Disable anti-theft features temporarily

Problem: "AT Command Failed" or "FLAG = 1" Error

Solutions:

• Check IMEI format (exactly 15 digits, no spaces)
• Try alternative AT commands: AT+EGMR=1,7,"IMEI"
• Ensure correct syntax with quotes
• Try writing IMEI via PC tools instead
• Check if engineering mode is disabled by manufacturer

Problem: Device Not Detected in Diagnostic Mode

Solutions:

• Reinstall Qualcomm or MediaTek USB drivers
• Try different USB ports (prefer rear panel ports)
• Use original or high-quality USB cable
• Disable antivirus temporarily
• Try different PC (driver conflicts common)
• For Qualcomm: Enter EDL mode manually
• For MediaTek: Use SP Flash Tool to verify connection

Problem: Wrong IMEI Written (Typo)

Solutions:

• Write correct IMEI immediately using same method
• IMEI can be overwritten multiple times safely
• Verify IMEI from device box before writing
• Double-check all 15 digits before confirming

Problem: "No Service" Persists After IMEI Repair

Solutions:

1. Check if IMEI is actually written (dial *#06#)
2. Verify IMEI matches original number
3. Check if device is blacklisted (use IMEI checker online)
4. Restore QCN or NVRAM backup
5. Flash complete stock firmware including modem
6. Check SIM card in another device
7. Verify APN settings are correct
8. Reset network settings

Legal and Ethical Considerations

When is IMEI Repair Legal?

Legal scenarios:

• ✅ Restoring original IMEI after firmware flash or hardware repair
• ✅ Fixing null/corrupted IMEI to restore device functionality
• ✅ Personal device repair for devices you own
• ✅ Professional repair services restoring original IMEI for customers

Illegal scenarios:

• ❌ Changing IMEI to different number (considered fraud)
• ❌ Unblocking stolen devices from carrier blacklists
• ❌ Bypassing network restrictions illegally
• ❌ Identity fraud using another device's IMEI
• ❌ Commercial services offering illegal IMEI changes

Country-Specific Regulations

Safety and Best Practices

Before Starting IMEI Repair

• ✅ Verify Original IMEI - Check device box, invoice, or label
• ✅ Backup Everything - QCN (Qualcomm) or NVRAM (MediaTek)
• ✅ Charge Battery - Minimum 50% to prevent interruption
• ✅ Download Stock Firmware - Have backup ROM ready
• ✅ Test USB Cable - Use original or high-quality cable
• ✅ Install Drivers - Proper drivers prevent connection issues
• ✅ Read Instructions - Follow steps carefully

During IMEI Repair

• ⚠️ Never Disconnect - Don't unplug USB during process
• ⚠️ Don't Rush - Take time to verify each step
• ⚠️ Double-Check IMEI - Verify all 15 digits before writing
• ⚠️ Keep Backup Handy - Have QCN/NVRAM backup accessible
• ⚠️ Monitor Progress - Watch for error messages

After IMEI Repair

• ✅ Verify IMEI - Dial *#06# to confirm
• ✅ Test Network - Insert SIM and check connectivity
• ✅ Check Signal - Verify signal strength
• ✅ Test Calls/Data - Make test call and browse internet
• ✅ Keep Backups - Store QCN/NVRAM safely for future

Frequently Asked Questions (FAQ)

Q: Can I repair IMEI without PC?

A: Yes, for MediaTek devices! Use the MTK Engineering Mode method with AT commands. Qualcomm devices require PC tools.

Q: Will IMEI repair void my warranty?

A: Most likely yes. IMEI modification is usually detectable and may void manufacturer warranty. However, if IMEI was corrupted during official service, they should restore it free.

Q: Is changing IMEI to a random number illegal?

A: Yes, in most countries. Only restore your device's original IMEI. Changing to a different IMEI is considered fraud.

Q: Can I unlock network carrier lock by changing IMEI?

A: No. Network locks are separate from IMEI. Contact your carrier for legitimate unlock codes or wait for contract completion.

Q: What if I don't have the original IMEI number?

A: Check:

• Device box or original packaging
• Purchase invoice/receipt
• Label under battery (removable battery)
• SIM tray slot (some devices)
• Google Find My Device (if previously registered)
• Contact manufacturer with proof of purchase

Q: Will IMEI repair fix a blacklisted device?

A: No. Blacklisting is carrier-level blocking based on IMEI number in shared databases. Even if you change IMEI (illegal), the device may still be tracked.

Q: My device shows generic IMEI (like 123456789012345). Can I fix it?

A: If it's a temporary generic IMEI assigned after firmware flash, yes. If it's hardware-related (faulty modem chip), IMEI software repair won't help.

Conclusion

IMEI repair is a valuable skill for mobile technicians and device owners facing network connectivity issues due to null, invalid, or corrupted IMEI numbers. This guide covered comprehensive methods for both Qualcomm and MediaTek devices, from simple AT command methods to advanced tools like QPST, QFIL, and SN Write Tool.

Key Takeaways:

• ✅ Qualcomm devices require QPST/QFIL and QCN backups
• ✅ MediaTek devices offer easier methods via Engineering Mode
• ✅ Always backup QCN or NVRAM before any IMEI operation
• ✅ Verify original IMEI from device box or documentation
• ✅ Use trusted sources like MobiFirms.com for firmware and tools
• ✅ Legal compliance - Only restore original IMEI, never change to different number
• ✅ Test thoroughly after repair to ensure network functionality

For Successful IMEI Repair:

1. Identify your chipset (Qualcomm or MediaTek)
2. Choose appropriate method based on device and tools available
3. Follow steps carefully without rushing
4. Backup critical partitions before making changes
5. Verify results and test network connectivity

Remember, IMEI repair should only be performed to restore your device's original IMEI number. Always ensure you're complying with local laws and regulations. When firmware issues arise, always download official stock ROMs from trusted sources to prevent future IMEI corruption.

Related Articles You May Find Helpful:

• How to Flash Firmware Using SP Flash Tool (MediaTek Guide)
• Qualcomm QFIL Tool: Complete Flashing Guide for Beginners
• How to Backup and Restore QCN Files on Qualcomm Devices
• MediaTek NVRAM Repair: Complete Guide to Fix Network Issues
• How to Fix "No Service" Error on Android Devices
• Complete Guide to Mobile Repair Tools Every Technician Needs
• How to Unbrick Qualcomm Devices Using EDL Mode
• MediaTek Chip-level Repair Guide for Technicians