TL;DR
- Every mobile handset has a unique 15-digit IMEI number; networks can block it from connecting if it has been reported lost, stolen, or associated with fraud.
- UK operators share blacklist data through the GSMA's IMEI database, meaning a phone blocked on one network is blocked on all UK networks.
- You can check an IMEI free of charge before buying a second-hand handset using services that query the shared database.
- Purchasing a blacklisted phone knowingly may constitute handling stolen goods under the Theft Act 1968; ignorance is a partial but uncertain defence.
- If your own phone is wrongly blacklisted, contact the operator that placed the block; Ofcom's complaints process is available if the operator does not resolve it.
What blacklisting is and how it works
Every mobile phone manufactured for sale in the UK is assigned an International Mobile Equipment Identity number — a 15-digit code unique to that specific handset, not the SIM inside it. When a device is reported lost or stolen, or is linked to fraud or an unpaid contract, the operator that received the report submits the IMEI to a shared industry database maintained under the auspices of the GSMA. This process is commonly called blacklisting, though the industry term in the GSMA's own documentation is EIR (Equipment Identity Register) blocking.
Because UK mobile network operators are contractually obliged to check the GSMA's Central Equipment Identity Register before allowing a device to register on their network, a phone that has been blacklisted by one operator will be refused service by all other UK operators as well. The phone may still power on, connect to Wi-Fi, and run apps, but it will not be able to send or receive calls, texts, or mobile data on any UK network.
Why phones end up blacklisted
The most common reason is theft: a victim reports their handset stolen to their operator, who raises a block. A second common route is loss — the owner reports the phone missing and requests a bar to prevent misuse. Operators can also blacklist a device linked to fraudulent activity, such as one obtained using a false identity, or a handset on which the contract payments have defaulted and the operator has pursued recovery action. In some cases, blacklisting arises from an administrative error, such as a handset being reported stolen in error by an insurance company after a claim is settled.
It is worth understanding that blacklisting the IMEI is distinct from barring the SIM. Barring the SIM (the subscriber identity) prevents calls and data being charged to that account but does nothing to prevent the same handset being used with a different SIM. Blacklisting the handset itself closes that gap: even inserting a fresh SIM from a different operator will not restore network access on a blocked device.
How to find your IMEI number
On virtually all smartphones, dialling *#06# on the keypad causes the IMEI (or, on dual-SIM devices, two IMEIs) to display on screen. It is also printed on the original retail box and, on many handsets, on a label beneath the battery or engraved on the SIM tray. iPhone users can find the IMEI in Settings > General > About. Android devices typically show it in Settings > About Phone > Status > IMEI information.
Recording your IMEI before buying a handset — or as soon as you receive a new phone — is recommended by both Ofcom and the Metropolitan Police's Immobilise scheme. If the device is stolen, having the IMEI ready speeds up the reporting process considerably and strengthens any insurance claim.
Running an IMEI check before buying second-hand
Several services in the UK offer IMEI lookups. Some are free and query only basic stolen-handset databases; others charge a small fee and return a more detailed report covering network lock status, whether the device is reported lost or stolen, and whether it is under a finance agreement. When buying a second-hand handset privately — through an online marketplace, a classified ad, or in person — running a check before handing over money is strongly advisable.
The GSMA itself does not operate a public consumer-facing lookup; rather, it licences access to operators and approved third parties. The relevant UK check is typically described as a check against the UK's national IMEI database (operated by industry body GSMA and fed by operator reports). Several comparison and consumer websites host free or low-cost lookup tools that tap into this data. A clean result means no block has been registered; it does not guarantee the phone was never stolen — if the owner has not yet reported it, no block will show.
| Check type | Typical cost | What it reports | Limitations |
|---|---|---|---|
| Basic free IMEI check | Free | Stolen/blacklisted status; network lock | Does not show outstanding finance; may use less-complete datasets |
| Paid full IMEI report | Typically £1–£5 | Blacklist, finance check, network lock, model verification | Finance data depends on lender participation; not exhaustive |
| Operator account check | Free (own account only) | Whether IMEI is blocked on that operator's network | Only accessible to customers of that operator |
| Immobilise / National Property Register | Free (registration free) | Whether item is registered as stolen by its owner | Only shows phones whose owners registered them; not a network block check |
| Police 'check-a-phone' services | Free (some forces offer this) | Whether IMEI appears in crime records | Availability varies by force; not a real-time network check |
What to do if you discover a phone is blacklisted
If an IMEI check reveals a block before you have purchased the handset, the straightforward advice is not to proceed with the purchase. Buying a phone that is listed as stolen knowing it to be so may constitute handling stolen goods, an offence under section 22 of the Theft Act 1968. If you are suspicious that the seller knew the phone was blacklisted, you can report the listing to the online platform and, if you believe a theft is involved, to Action Fraud (the UK's national fraud and cybercrime reporting centre).
If you have already purchased a handset and then discover it is blacklisted, your position depends on the circumstances. If you bought in good faith from a private seller, you may have a civil claim against that seller for selling goods they did not have the right to sell, under the Consumer Rights Act 2015 where applicable or general contract law. The handset itself remains the property of whoever it was originally stolen from or the finance provider if under a hire-purchase agreement; you do not acquire title simply by paying for it. Reporting the situation to Action Fraud and notifying the original operator are the recommended first steps.
Resolving a wrongful blacklisting
Administrative errors do occur. An insurance company may raise a stolen flag on a phone that has since been found; an operator may log the wrong IMEI against a theft report. If your own handset stops working on UK networks unexpectedly, checking the IMEI is the diagnostic first step. If a block is confirmed, contact your operator's customer services team: they can query the block's origin, liaise with the operator that placed it, and request removal if the block was raised in error.
Operators are required under their Ofcom licence conditions to handle complaints fairly and in a timely manner. If your operator fails to resolve a wrongful blacklisting within eight weeks, or you reach deadlock, you are entitled to escalate to one of the two Ofcom-approved Alternative Dispute Resolution (ADR) schemes — currently the Ombudsman Services: Communications scheme and the Communications and Internet Services Adjudication Scheme (CISAS). Ofcom's website sets out how to identify which scheme applies to your operator.
What this means in practice
Priya, living in Manchester, buys a used iPhone from an online marketplace for £280. The listing looks genuine and the phone powers on normally. Two days after receiving it, she inserts her SIM and finds there is no network signal — just a “SIM not supported” or “no service” message. She dials *#06# and notes the IMEI, then runs a paid IMEI check online. The result shows the handset is listed as stolen and blacklisted by a major UK operator. She does not know the seller personally — it was a private listing. Priya contacts Action Fraud online, logs a report, and messages the seller via the marketplace platform requesting a refund, copying in the platform's buyer-protection team. She retains all screenshots and payment records. The marketplace's resolution process requires the seller to refund within a set timeframe; if no refund is received, Priya can raise a chargeback with her bank under the Consumer Credit Act or debit-card protection rules. Her consumer law position is strong because she acted in good faith and can demonstrate she did not know the phone was blacklisted at the time of purchase.
Related Guides
How we verified this
This article draws on Ofcom's published guidance on mobile phone security and the complaints and ADR framework; GSMA documentation on the Equipment Identity Register; the text of the Theft Act 1968 as published on legislation.gov.uk; the Consumer Rights Act 2015 on legislation.gov.uk; and Action Fraud's public guidance on reporting stolen mobile phones.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
What does it mean if a phone is blacklisted?
A blacklisted phone has had its IMEI number added to the GSMA's shared Equipment Identity Register, which all UK mobile operators check before allowing a device to connect. This means the handset cannot make or receive calls, send texts, or use mobile data on any UK network, regardless of which SIM card is inserted. The phone will still function on Wi-Fi.
How do I check if a phone is blacklisted before buying?
Ask the seller for the IMEI (or dial *#06# if you can inspect the phone in person) and run it through a free or paid IMEI check service. These services query the UK national IMEI database, which is fed by operator reports. A clean result means no block is currently registered, though it cannot guarantee the phone was not stolen if the theft has not yet been reported.
Can a blacklisted phone be unblocked?
Yes, but only by the operator that placed the block, or in cases of error, by coordinating with the relevant operator. Legitimate unblocking happens when a stolen phone is recovered and returned to its owner, or when a block was placed in administrative error. Third-party services claiming to unblock any phone for a fee are typically scams and should be avoided.
What should I do if my phone gets blacklisted?
First establish which operator placed the block by contacting your network. If the block was placed correctly (for example after a theft report you made), ask them to remove it once the phone is recovered. If the block appears to be an error, raise a formal complaint with the operator. If unresolved within eight weeks, escalate to the relevant Ofcom-approved ADR scheme.
Does a blacklisted phone work with any SIM?
Not on UK mobile networks. Because all UK operators share the same GSMA Equipment Identity Register, a blacklisted IMEI is blocked across all networks. Inserting a different SIM — including a SIM from a different UK operator — will not restore mobile connectivity. The phone will still work on Wi-Fi for apps, calls over the internet, and similar functions.
