What does this tool actually check?
This tool runs two checks instantly in your browser: 15-digit format validation (every IMEI must be exactly 15 numeric digits) and Luhn checksum validation (the last digit is mathematically derived from the first 14, so typos and many fabricated IMEIs fail immediately). It also extracts the TAC (Type Allocation Code), the first 8 digits, which identifies the device model and manufacturer.
What this tool does not do: it does not query GSMA Device Registry, carrier blacklists, iCloud Activation Lock status, or financed-device status. Those queries require either paid third-party APIs or authorised reseller access. The cards below tell you which source to use for each status check.
After format validation, what should you check next?
For wholesale lots, format validation is the first triage step. Once you have a list of IMEIs that pass format and Luhn, the next checks are blacklist status, carrier-lock status, and (for Apple devices) iCloud Activation Lock status. Different sources cover different signals, so most wholesale buyers run a sample through multiple services.
Why does Luhn validation catch problems before you pay?
The 15th digit of every legitimate IMEI is a Luhn checksum computed from the first 14. When sellers fabricate IMEIs (or when a manifest spreadsheet drops a leading zero), the Luhn check fails. In our experience with wholesale lots, format and Luhn failures correlate strongly with one of three problems:
- Typos in the seller's manifest. Most common cause. Usually fixable by the seller pulling fresh IMEIs from inventory.
- Counterfeit or refurbished devices with fabricated IMEIs. Some grey-market refurbishers reflash IMEIs to hide blacklist status. The original IMEI fails Luhn because it was never a real Apple/Samsung-issued number.
- Spreadsheet formatting damage. Excel auto-converts long numeric strings to scientific notation, dropping precision. A 15-digit IMEI becomes "3.56938E+14" or loses trailing digits. Always request manifests as text-format CSV.
What does the TAC (Type Allocation Code) tell you?
The first 8 digits of every IMEI form the TAC. The first 2 identify the reporting body (01 = PTCRB / North America, 35 = BABT / UK + EU, 86 = TAF / China, etc.). The remaining 6 identify the specific device model and manufacturer.
For wholesale buyers, the TAC is a quick sanity check that the IMEI list matches the model claimed in the offer. If a seller says "500 iPhone 15 Pro Max units" but the TACs map to a mix of older models, the manifest is wrong. The tool above shows the TAC for every IMEI.
How should I integrate this into my wholesale workflow?
Use this as the first step in pre-payment due diligence. Run all IMEIs through format + Luhn check, then send a sample (10-50 IMEIs depending on lot size) through a paid blacklist + iCloud-lock service. Reconcile any failures with the seller before paying. Larger lots warrant 100% IMEI screening; lots under 50 units usually justify only sample checking.
Frequently asked questions
Is this tool free?
Yes. Format and Luhn validation are computed entirely in your browser using JavaScript. We don't store the IMEIs, log them, or transmit them anywhere. There's no signup or limit on usage.
How many IMEIs can I check at once?
Up to 100 per run, to keep the interface responsive. For larger lots, run multiple batches or contact us for an export-friendly version.
Will this tell me if an IMEI is blacklisted?
No. Blacklist databases (GSMA, CheckMEND, Swappa) require paid API access or authorised account credentials and we don't proxy them. This tool covers the format and Luhn checksum layer; the cards above link to the recommended services for the next step.
What about iCloud Activation Lock?
Same answer. iCloud status requires Apple GSX access (Apple Authorised Service Provider) or a paid third-party service. The format check confirms the IMEI is a valid Apple-issued number; the iCloud query is a separate step.
What if my IMEIs are all flagged invalid?
Three common causes: the manifest was opened in Excel and lost precision (request a text-format CSV); the seller has the wrong column (sometimes ICCID or serial is sent instead of IMEI); or the IMEIs are genuinely fabricated. In the third case, walk away from the lot.
Source verified stock on Aikon
Aikon is the B2B wholesale electronics trading platform. Every seller is a verified company; offers include structured fields for region, condition, and lock status. Free for verified companies.