What an IMEI actually is
An IMEI — International Mobile Equipment Identity — is a 15-digit number that identifies a piece of cellular hardware. It belongs to the radio inside the device, not to you, not to your SIM and not to your phone number. Swap the SIM and the IMEI stays. Port your number and the IMEI stays. Factory reset the phone and the IMEI stays.
Because it identifies hardware, a dual-SIM phone has two IMEIs, one per radio. Devices with a modem but no phone function — tablets, LTE routers, car telematics units — have one as well.
How the 15 digits are structured
| Digits | Field | What it tells you |
|---|---|---|
| 1–2 | Reporting Body Identifier | Which regional body issued the allocation. 35 is BABT in the UK, 01 is PTCRB in North America, 86 is TAF in China. |
| 1–8 | Type Allocation Code | The model. Every unit of a hardware variant shares this. |
| 9–14 | Serial number | Assigned by the manufacturer, unique within that TAC. Carries no decodable meaning. |
| 15 | Check digit | A Luhn checksum over the first 14 digits. Catches typos, not forgeries. |
The check digit, and what it does not prove
The final digit is computed with the Luhn algorithm — the same mod-10 checksum used on payment cards. Double every second digit from the left of the 14-digit payload, subtract 9 from any result above 9, sum everything, and the check digit is whatever brings the total to a multiple of ten.
This is worth being precise about, because it is the most misunderstood thing about IMEI checking. A valid check digit tells you the number was transcribed correctly. It does not tell you the number was ever issued, that a device carrying it exists, or that the device is legitimate. Anyone can generate a syntactically valid IMEI in a few lines of code. Passing the check is a floor, not a verdict.
What this tool cannot tell you
We validate the check digit and read the reporting body and TAC. We do not check whether a device has been reported lost or stolen — that lives in national registries we have no lawful access to, and any free site claiming otherwise is guessing.
Blacklisting is handled per country:
- India — the Central Equipment Identity Register at ceir.gov.in. See our step-by-step guide to blocking a stolen phone.
- United States — the GSMA Device Registry feeds carrier blacklists. Most carriers offer a device-eligibility lookup; there is no single public national check.
- UK and much of the EU — commercial services aggregate insurer and police reports. Paid, and coverage varies by country.
Buying a used phone
Do this with the handset in front of you. Dial *#06#, then compare what appears against the IMEI printed in the SIM tray and the one in Settings. If those three disagree, the device has been tampered with — walk away.
Then run the IMEI through the local registry before money changes hands.
IMEI and IMEISV
You will occasionally see a 16-digit number. That is an IMEISV, where the check digit is replaced by a two-digit software version. Operators use it to identify firmware revisions. Drop the last two digits and check the first 14 as a prefix — this tool will tell you the missing 15th digit.