IMEI Numbers Explained: Structure, TAC and Check Digit
Every mobile device has an IMEI — a 15-digit identifier used by networks and device-management systems. If your software stores or validates IMEIs, you need structurally valid test numbers.
What the digits mean
- TAC (8 digits): Type Allocation Code — identifies the make and model.
- Serial (6 digits): unique to the device within that model.
- Check digit (1 digit): calculated with the Luhn algorithm.
Validating an IMEI
Apply the same Luhn check used for card numbers to all 15 digits. A valid IMEI totals a multiple of 10. This catches typos when users enter IMEIs manually for warranties or insurance claims.
Legal note
Changing a device’s real IMEI is illegal in many countries. Generated IMEIs are for software testing only — MDM enrolment, repair-shop systems and telecom input validation.
Pro tips
- Dial *#06# on any phone to see its real IMEI.
- Test inputs with spaces and slashes, as printed on boxes.
- Store IMEIs as strings to preserve leading zeros.