IMEI Numbers Explained: A Developer's Guide

If you build anything that touches mobile devices — MDM systems, telecom apps, device management platforms, repair shop software — you've probably dealt with IMEI numbers. What Is an IMEI? IMEI = International Mobile Equipment Identity. A unique 15-digit number assigned to every GSM mobile device. Dial *#06# on any phone to find yours. The Structure TAC (8 digits) + Serial (6 digits) + Check digit (1, Luhn algorithm) TAC — Type Allocation Code First 8 digits identify device model and manufacturer, assigned by GSMA. Luhn Algorithm Same checksum used for credit cards. Catches single-digit and transposition errors. function luhnCheck ( imei ) { let sum = 0 ; for ( let i = 0 ; i < 14 ; i ++ ) { let digit = parseInt ( imei [ i ]); if ( i % 2 === 1 ) { digit *= 2 ; if ( digit > 9 ) digit -= 9 ; } sum += digit ; } return ( 10 - ( sum % 10 )) % 10 ; } Why Developers Need Test IMEIs MDM platforms, telecom systems, device buyback apps, repair shop software, inventory tracking — all need valid IM