The next 6 digits, identifying the specific individual device.

Generated IMEIs are for testing and development purposes only. Modifying a device's original IMEI is illegal in many jurisdictions.

The EFS partition (Qualcomm) or NVRAM (MediaTek) got corrupted. Legitimate Fix:

: Every mobile device has a unique 15-digit IMEI number. For dual-SIM devices, there are typically two separate IMEIs—one for each SIM slot.