| Position | Digit | Operation | Processed Value | Sum Contribution |
|---|
Understanding IMEI Structure and Luhn Verification
An International Mobile Equipment Identity (IMEI) is a 15-digit unique code assigned to global mobile telecommunication devices. The structure follows strict GSMA standards to ensure proper identification on cellular networks such as Jazz, Telenor, Zong, and Ufone in Pakistan.
15-Digit IMEI Structural Breakdown
An IMEI number consists of four distinct sub-components:
- TAC (Type Allocation Code) – First 8 Digits: Includes the 2-digit Reporting Body Identifier (RBI) indicating the GSMA registry group, followed by 6 digits identifying the specific model and manufacturer.
- SNR (Serial Number) – Next 6 Digits (Positions 9 to 14): An individual serial number assigned by the manufacturer to distinguish each handset.
- CD (Check Digit) – 15th Digit: A single verification digit calculated using the Luhn Algorithm (Modulo 10) to validate the preceding 14 digits and prevent entry errors.
The Luhn Algorithm Calculation Steps
The Luhn algorithm (also known as the “modulus 10” algorithm) verifies the integrity of an IMEI through the following math steps:
| Step | Action Required | Example Demonstration |
|---|---|---|
| Step 1 | Take the first 14 digits of the IMEI number. | 86512304567890 |
| Step 2 | Double the value of every second digit starting from right to left (even-positioned digits from the right). | Odd digits stay same; even digits multiplied by 2. |
| Step 3 | If doubling a digit yields a number ≥ 10, sum its individual digits (e.g. 7 × 2 = 14 → 1 + 4 = 5). | Values reduced to single digits 0–9. |
| Step 4 | Sum all processed digits together. If total % 10 == 0, check digit is 0. Otherwise, Check Digit = (10 – (Total % 10)). | Total Sum = 59 → 10 – (59 % 10) = 1. Check digit is 1. |
Reporting Body Identifiers (RBI) List
The first two digits of the TAC represent the GSMA-approved issuing body:
- 35: BABT (British Approvals Board for Telecommunications – Global / UK)
- 86: TAF (Telecommunication Terminal Equipment Protection Association – China)
- 01: PTCRB (PCS Type Certification Review Board – USA)
- 51: MSA (India)
Frequently Asked Questions (FAQs)
What is an IMEI number and why is it important?
An IMEI (International Mobile Equipment Identity) is a unique 15-digit code assigned to every mobile device. It is used by GSM networks to identify valid devices, block lost or stolen phones, and verify PTA compliance in Pakistan.
How does the Luhn Algorithm verify an IMEI number?
The Luhn algorithm (Mod 10 checksum) calculates a check digit based on the first 14 digits of the IMEI. Every second digit is doubled, and the sum of all individual digits must be divisible by 10 for the IMEI to be mathematically valid.
What is the TAC (Type Allocation Code) in an IMEI?
The TAC consists of the first 8 digits of an IMEI number. It identifies the specific manufacturer and model of the mobile device as registered with the GSMA.
How can I check the IMEI number on my mobile phone?
You can view your device’s IMEI by dialing *#06# on your phone’s keypad, or by checking the device settings under About Phone, or looking at the original box packaging.