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What Is the TAC Code in an IMEI Number?

5 min readUpdated 6/1/2025

Understanding the TAC Code in IMEI

Every 15-digit IMEI number begins with an 8-digit TAC — Type Allocation Code. This is the segment that identifies the device type and manufacturer, and it's what IMEI check services use to return device information.

IMEI Number Structure

A standard IMEI breaks down as follows:

  • Digits 1–8: TAC (Type Allocation Code) — Identifies the device model and manufacturer
  • Digits 9–14: Serial Number (SNR) — Unique serial within the same model
  • Digit 15: Check Digit (CD) — Calculated via Luhn algorithm to validate IMEI legitimacy

What the TAC Reveals

The TAC is registered with the GSMA (Global System for Mobile Communications Association) in the Type Allocation Code database. It stores:

  • Manufacturer name (Apple, Samsung, Xiaomi, etc.)
  • Device model and variant
  • Network bands and technology supported
  • Release year and region of manufacture

TAC and IMEI Validation

When you run a free IMEI check, the TAC is decoded first. If the TAC is unrecognised (not in the GSMA database), the device is likely a clone or fake. All genuine devices from legitimate manufacturers have registered TAC codes.

Why TAC Matters for Buyers

The TAC is the foundation of all IMEI-based device verification. It cannot be changed without physically altering the device's firmware — making it a reliable identifier. A device with a TAC that doesn't match the claimed brand is definitively fake.