A phone with a null, invalid, or 0000 IMEI loses its network identity — no signal, no calls, no mobile data. This often happens after a flash, an NVRAM error, or a bad repair. The Aftersales ToolBox (part of the Transsion service suite) is the go-to tool for restoring IMEI on MediaTek (MTK) and Unisoc/SPD phones. This guide walks through the full IMEI repair process step by step.

What Is IMEI and Why Does It Break?

IMEI (International Mobile Equipment Identity) is the unique 15-digit number that identifies your phone to the mobile network. It is stored in a protected area of the phone's memory (NVRAM/NVData on MTK, or the equivalent on SPD).

IMEI can become corrupted or wiped after a full firmware flash, a failed NVRAM write, water damage, or an incorrect repair. When that happens, dialing *#06# shows blank, zeros, or an invalid number, and the phone can't connect to any network.

What You Will Need

  • A Windows PC
  • The Aftersales ToolBox (correct version for your model)
  • The proper USB drivers (MTK VCOM or SPD)
  • The phone's original IMEI (printed on the box, under the battery, or on the sticker)
  • A good USB cable
  • An internet connection (newer versions fetch an attestation key online)

Understanding the Two IMEI Repair Methods

  • Older method: required both BP and AP files extracted from the firmware to rebuild the database before writing IMEI.
  • Newer method: the Aftersales ToolBox connects online, updates an Attestation Key, and writes IMEI directly — no BP/AP files needed. This is faster and works on most current models.

Step 1: Install Drivers and Launch the Tool

Install the correct chipset driver, then run the Aftersales ToolBox as administrator. Choose your platform (MTK or SPD) inside the tool.

Step 2: Find the Correct IMEI

Never invent an IMEI. Use the phone's genuine number printed on the box, the sticker under the battery, or the original label. Restoring the real IMEI keeps the device legal and correctly identified on the network. Most phones have two IMEI slots (IMEI1 and IMEI2) for dual SIM.

Step 3: Connect the Phone in the Right Mode

  1. Power the phone off.
  2. Hold Volume Up + Volume Down (or the mode the tool requests).
  3. Connect the USB cable.

The tool detects the device and shows its COM port.

Step 4: Write the IMEI

  1. Enter IMEI1 (and IMEI2 for dual SIM) exactly as printed.
  2. If using the online method, let the tool update the attestation key first.
  3. Click Write IMEI and wait for the success message.

Step 5: Verify

Reboot the phone and dial *#06#. The restored IMEI should now display correctly, and the phone should register on the network with signal restored.

Common Problems and Fixes

IMEI writes but shows null after reboot. The NVRAM/database wasn't rebuilt. Use the correct firmware's BP/AP files or the online attestation method.

"Write failed" error. Wrong tool version or driver. Match the ToolBox version to the model and reinstall the driver.

Only IMEI1 restored on a dual-SIM phone. Write both slots; some tools need each entered separately.

No signal even with correct IMEI. The baseband/modem may be corrupted — reflash the firmware first, then repair IMEI.

Best Practices

  • Always write the genuine IMEI printed on the device.
  • Reflash firmware first if the baseband is damaged, then repair IMEI.
  • Keep the ToolBox and drivers updated for online attestation support.
  • Record the original IMEI before any repair for reference.

Frequently Asked Questions

Is it legal to repair IMEI? Restoring a phone's original, genuine IMEI after it was lost in a repair is legitimate. Changing a phone's IMEI to a different number is illegal in most countries.

Why is my IMEI 0000 after flashing? A full flash can wipe the NVRAM area that stores IMEI. Repairing it with the ToolBox rewrites that data.

Do I still need BP and AP files? On newer models, no — the online attestation-key method replaces them. Older models may still require BP/AP files from the firmware.

Will IMEI repair fix no-signal issues? Only if the problem was the missing IMEI. If the modem/baseband is corrupted, reflash the firmware first.

Understanding NVRAM and Why Backups Matter

On MediaTek phones, IMEI and other calibration data live in a protected region called NVRAM (Non-Volatile RAM), sometimes stored as NVData and NVCFG partitions. This is where the modem keeps the values it needs to register on a network. When NVRAM is damaged — by a wrong flash, a format-all operation, or water corrosion — the phone loses IMEI, signal, or both.

This is why professional technicians read and save a full NVRAM/firmware backup before any risky operation. If something goes wrong later, you can restore the exact original calibration instead of rebuilding it from scratch. On SPD/Unisoc devices the equivalent data sits in the modem/NV area, and the same rule applies: back up first.

A good habit is to keep a labeled folder of NVRAM backups per model, so future repairs on the same device are faster. When a customer's IMEI is beyond simple repair because the whole NV area is corrupted, restoring a matching backup or reflashing the full firmware with the correct database is often the only clean fix.

Where do I find my phone's original IMEI? Check the retail box, the sticker under the battery or in the SIM tray area, or the label on the back of the device. Dual-SIM phones list two numbers, IMEI1 and IMEI2.

Can I repair IMEI without the original number? You should not. Restoring a device's own genuine IMEI is the only legitimate repair. If the label is missing, the number can sometimes be recovered from an NVRAM backup taken earlier.

Does IMEI repair work on locked bootloaders? Yes, because the ToolBox writes IMEI through the modem/NV area in download or diag mode, which does not depend on the bootloader being unlocked.

Why does signal drop again after a few hours? This usually points to a partially corrupted modem, not just IMEI. Reflash the full stock firmware for the exact model to rebuild the modem, then repair IMEI once more and retest.

A Note on Responsible Use

IMEI repair should only restore a device's own genuine IMEI, and only on phones you own or are authorized to service. Writing a false or someone else's IMEI is illegal. Always use the number printed on the original device and source tools from trusted channels.

Conclusion

Restoring IMEI on MTK and SPD phones with the Aftersales ToolBox is a straightforward repair once you have the right driver, the genuine IMEI, and the correct tool version. Connect the phone, enter IMEI1 and IMEI2 exactly as printed, use the online attestation method where supported, and verify with *#06#. If signal is still missing, reflash the firmware first, then repair IMEI — and always work only with a device's own genuine number.