Abstract The MTK Write IMEI Tool is a low-level utility designed to restore, repair, or rewrite the International Mobile Equipment Identity (IMEI) numbers on smartphones powered by MediaTek (MTK) processors. This paper examines the tool's architecture, operating principles, common use cases (e.g., restoring null IMEI after firmware corruption), associated legal and security risks, and a step-by-step functional guide for authorized service technicians. 1. Introduction The IMEI is a 15-digit unique identifier for mobile devices, critical for network authentication, device tracking, and theft prevention. On MediaTek-based devices, the IMEI is stored in the NVRAM (Non-Volatile Random Access Memory) partition, specifically within the APNVRAM or BPLGU files. Corruption of this partition—due to failed OTA updates, flashing incorrect firmware, or using format-all tools like SP Flash Tool—can result in "Null IMEI" or "Invalid IMEI," rendering the device unable to connect to cellular networks. The MTK Write IMEI Tool provides a direct method to reprogram these values. 2. Tool Architecture & Requirements The tool communicates with the device via Meta Mode (MediaTek's proprietary engineering mode) or BootROM interface.