- "Clean" is a block list answer only. It says the IMEI was not flagged on the list the service reads, at the moment it was read.
- "NR/LTE/WCDMA/GSM" is a capability list for the model: 5G, 4G, 3G, 2G. It is not a status and it says nothing about the individual handset.
- Lock fields are independent of both. Carrier lock, FRP, iCloud Activation Lock, MDM and Knox each answer a different question.
- TAC, brand and model fields come from the GSMA TAC allocation record, so they describe what the model should be, not what arrived in the box.
- Block list status is the field most likely to change after a check. Re-check the IMEIs on arrival, not only at the quote stage.
The short answer
An IMEI check result is one report keyed to one 15-digit IMEI, assembled from several sources that a single screen makes look like one verdict. Read it as three groups: a block list status, a set of model attributes from the type allocation record, and a set of lock states. A result can be clean in the first, list LTE and NR in the second, and still be locked in the third. The green word at the top answers only the first.
What does "Clean" mean on an IMEI check?
"Clean" means the IMEI was not found on the block list the checking service queries, at the moment of the query. Nothing more.
The underlying list is the GSMA block list, which the GSMA describes as a list of IMEIs associated with devices that should be denied service because they have been reported as lost, stolen, faulty or otherwise unsuitable for use (GSMA, IMEI Database). The GSMA's own service, GSMA Device Check, never prints the word "clean". It returns "NO - not flagged on GSMA Block List" in green, or "YES - flagged on GSMA Block List" in red with the reason in the device history (GSMA Device Check FAQs). "Clean" is the shorthand third-party checkers print in place of that green status.
What a clean status does not prove is the part worth memorising:
- It does not prove ownership. A device can be stolen and still be clean, because nobody has reported it yet.
- It does not prove the device is unlocked. Carrier lock is a separate field held by carriers, not by the block list.
- It does not prove condition or grade. Battery health, water damage and repair history are not in the record.
- It does not prove the handset matches the manifest. The model shown belongs to the TAC, not to the object in front of you.
- It is not permanent. A finance default or a late theft report can add the IMEI to the list weeks after your check.
Read "clean" as "no known report as of now". The longer treatment of the status wording sits in GSMA blacklist status: clean, blocked and unknown.
What does NR / LTE / WCDMA / GSM mean on an IMEI report?
It is a list of the radio technologies the model supports, one per mobile generation. It is a capability list, not a status, and it never turns red.
This row causes most of the confusion, because it sits under a green status word and looks like part of the verdict. It is not. It comes from the type allocation record: a manufacturer applying for a Type Allocation Code submits the manufacturer name, the device models and selected technical capabilities such as the frequency bands supported, and the GSMA validates and allocates the TAC before production (GSMA, IMEI Database).
| Label on the report | Generation | What it is | What to do with it |
|---|---|---|---|
| GSM | 2G | The original digital cellular standard, voice and SMS plus slow data | Relevant only where 2G is still switched on; many markets have retired it |
| WCDMA (UMTS) | 3G | The wideband CDMA air interface used by UMTS networks | Being switched off in many markets; check the destination network before buying 3G-only stock |
| CDMA | 2G/3G | A separate legacy family, mostly historic, seen on older North American and Asian models | Treat as end of life; these devices are usually not resellable as working handsets |
| TD-SCDMA | 3G | A 3G variant deployed mainly in mainland China | A strong hint that the unit is a China-market variant, check the model code |
| LTE | 4G | The 4G radio, still the workhorse of most networks | The practical floor for resale in most markets today |
| NR | 5G | New Radio, the radio technology 3GPP defined for 5G | Confirms the model is a 5G variant, which often separates two otherwise identical SKUs |
NR is the label buyers most often mistake for an error code. 3GPP states plainly that 5G's radio technology is called NR, for New Radio (3GPP, 5G System Overview). A row reading "NR/LTE/WCDMA/GSM" is saying: this model does 5G, 4G, 3G and 2G. The print order carries no meaning.
Two cautions. The list describes the model, so it is identical for every unit sharing that TAC, including the one with a dead modem. And supported technology is not supported bands: a model can list LTE and still lack the bands a destination network needs. Plain definitions sit side by side in the glossary entry on GSM, WCDMA and LTE.
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What does "Blacklisted" or "Blocked" mean, and which list?
It means the IMEI appears on a list of devices that should be denied service. The follow-up question is always which list, because there are three kinds and they do not agree with each other.
The GSMA Device Registry is the shared layer. Operators, manufacturers, insurers and inventory managers report stolen IMEIs into it, and the block list inside the registry acts as a central equipment identity register so operators can share their individual block lists (GSMA, IMEI Database). A device blocked there is intended to be unusable across every connected network, which makes a red status here the most serious of the three.
Carrier lists are the second kind. A network can bar a handset on its own system for reasons that never reach the shared registry, most often an unpaid device finance agreement. A unit can be clean on the GSMA list and barred by the carrier that sold it. National registries are the third kind: several countries run their own equipment identity registers with their own reporting rules, so an IMEI can be blocked in one country and usable in another. A single green line is not a global clearance, and a checker that names the list it queried is worth more than one that only prints a colour.
If your report shows a code rather than a word, the GSMA blacklist status decoder explains what each common status string means.
What do the lock fields mean: carrier lock, FRP, iCloud, MDM and Knox?
Lock fields answer "can a new owner set this device up and use it", which is a different question from "is it blocked". A handset can be clean on every list and still be unusable because of any one of these.
| Field | What it means | Who can clear it | Effect on a wholesale lot |
|---|---|---|---|
| Carrier lock / SIM lock | The handset only accepts SIM cards from one network | The carrier that applied it, on request, subject to its own rules | Restricts the resale market and the price; check before agreeing a grade |
| FRP (Factory Reset Protection) | After a reset, the Android device asks for the Google account that was signed in before the wipe | The original account holder, by signing in or removing the account before the device leaves them | A triggered unit cannot be set up at all until the account is cleared at source |
| iCloud lock / Activation Lock | The iPhone or iPad is tied to an Apple Account and asks for it on activation | The original Apple Account holder, by removing the device from Find My, or Apple's own process | The same practical outcome as FRP: the unit cannot be activated |
| MDM enrolment | The device is enrolled in an organisation's mobile device management, so policies reapply after a wipe | The organisation that owns the enrolment, by releasing the device from its MDM | Common on ex-corporate lots; ask for release confirmation, not just a wipe |
| Knox status | Samsung's hardware-backed security state, including a warranty bit and Knox Guard style controls | Depends on the control; a Knox Guard lock is released by the enrolling organisation | A tripped warranty bit affects secure features and value; a Knox Guard lock blocks use |
Two practical rules follow. An absent lock field is not a cleared lock field: many reports do not query these states at all, and a blank means untested. And the only legitimate route out of an account lock runs back through the original account holder or the vendor's own process, so for a buyer the fix is commercial, not technical. Have the seller clear accounts before shipping, and make "no account locks on arrival" a stated condition rather than an assumption.
FRP is the lock traders ask about most, including the exact string "FRP status: triggered". The full explanation is in what FRP lock means.
What do TAC, model, brand and "IMEI model check" fields tell you?
They tell you what the manufacturer registered for that Type Allocation Code. They describe the model, and they are the fastest way to catch a manifest that does not match the stock.
The IMEI has three parts: a Type Allocation Code, a serial number and a check digit (GSMA, IMEI Database). The first eight digits are the TAC, and everything printed under brand, model, marketing name, storage variant, region variant and network technology comes from the record attached to it. An "IMEI model check" or "IMEI TAC lookup" is a lookup of the manufacturer's own declaration.
That makes three checks free. Does the brand and model match the offer? Does the variant match, particularly storage and region, where a manifest most often drifts? And does the check digit validate, because an IMEI that fails its own checksum is a transcription error or an invented number rather than a device. Run the structural parts on the free IMEI check tool; the anatomy of the number is broken down in how an IMEI is built.
What they cannot tell you is the state of the individual unit. Two handsets sharing a TAC return identical rows whether one is mint and the other has a swollen battery. Use the TAC record to test the paperwork, not the hardware.
What does "Unknown" or "No data" mean?
It means the service could not answer. That is a third outcome sitting between clean and blocked, and it should change what you do next.
The ordinary reasons: the TAC is too new and has not propagated to the checker; the IMEI is mistyped, in which case the check digit usually fails first; the service does not cover the list or carrier you care about, common for regional data; or the field needs a commercial feed, so a free checker returns nothing rather than a negative.
The response to unknown is to narrow it. Re-enter the number and confirm the check digit validates. Try a second source that names the list it queries. If the empty field is a lock state, test it physically: a foreign SIM answers the carrier lock question in seconds, and a setup attempt answers the account lock question. Treating unknown as clean is the most expensive reading mistake on a lot, because it converts a missing answer into a positive one.
How to read a bulk IMEI check for a wholesale lot
On a lot you are not reading one report, you are reading a distribution. The useful signals are the exceptions: the rows that disagree with the rest of the file.
- Validate the file before you pay for lookups. A structural pass catches the rows that are not valid IMEIs at all. The bulk IMEI check tool does format and check digits on a pasted list, and the IMEI check digit calculator settles a single disputed number.
- Look for duplicates. Repeated IMEIs in one manifest are usually a spreadsheet error, occasionally a padded count. Either way it needs an answer before the lot ships.
- Group by TAC. A lot described as one model should resolve to a handful of TACs. A long tail of unexpected ones means mixed models, mixed regions, or a manifest assembled from several sources.
- Flag mismatched models. Compare the model returned by the TAC lookup against the line description. A few mismatches are normal in mixed grades; a systematic mismatch is a different lot from the one you quoted.
- Sample first, then re-check on arrival. A representative sample tells you whether the manifest is honest. The full pass belongs on the units you actually receive, because that is the set you will resell.
A single blocked IMEI in a large lot is not automatically a problem; it may be one unit to pull. A cluster of them, or blocked units concentrated in one TAC or serial range, describes the lot's origin and is worth raising with the seller before shipping rather than after.
Which fields change over time, and when to re-check
Half the report is static and half is a snapshot. Knowing which is which tells you when a second check is worth running.
| Field | Stability | Why it changes | When to re-check |
|---|---|---|---|
| TAC, brand, model, network technology | Fixed | Tied to the type allocation record for that model | Never, unless the IMEI itself was mistyped |
| Check digit validity | Fixed | A property of the 15 digits themselves | Never |
| Block list status | Changes | New reports of loss, theft, fraud or unpaid finance land continuously | On arrival, and again before you resell if the unit sat in stock |
| Carrier lock | Changes | A carrier can unlock a device, and a returned handset can be re-flagged | On arrival, physically with a foreign SIM |
| FRP, Activation Lock, MDM, Knox | Changes | Depends on what the previous owner or organisation did before or after the sale | On arrival, by attempting setup on a sample |
The consequence is a timing rule. A check at the quote stage tells you whether to keep negotiating. A check when the goods land tells you what you actually bought, and that is the one that matters, because block list status can move in the gap between the two.
Reading an IMEI report in order
- Confirm the IMEI is 15 digits and the check digit validates.
- Read the block list status, and note which list the service queried.
- Read the TAC-derived rows as a test of the manifest, not of the unit.
- Read NR/LTE/WCDMA/GSM as capability, then check the specific bands for the destination market.
- Read each lock field separately, and treat a blank field as untested.
- Re-run the block list check when the goods arrive.
An IMEI report is a good document once you stop reading it as a verdict. Three groups, three questions, and one of them expires. Read it that way and the green word at the top goes back to meaning what it actually says.