UK spam number checker

How the spam check works

Three independent signals power the spam verdict on every per-number page:

• Community spam reports. Approved threads in the WhoCalledLookup community that have tagged this UK number. Each thread is moderated against our editorial policy — duplicates, vendettas and defamation are removed before anything is published.
• AI internet check. A live, on-demand summary of what the public web — forums, scam-reporting databases, news mentions — says about the exact digits. The AI cites its sources where it can, so you can audit the underlying evidence.
• Ofcom range holder. Structured data on which UK communications provider Ofcom originally allocated the block to. A number from an unfamiliar reseller block with no consumer-facing brand is an amber flag; a number from a major UK bank’s known outbound CLI block is a green one.

What counts as a UK spam number?

“Spam” covers a wide spectrum — different responses are appropriate for each. Loosely:

• Outright fraud. Bank-impersonation, courier phishing, HMRC arrest scams, tech-support remote-access scams. These actively try to steal money or credentials. Hang up immediately; never share codes, OTPs or card details on a call you didn’t initiate.
• Premium-rate ring-back. One-ring missed calls from 070 personal-numbering ranges that bill the caller heavily for calling back. Don’t return the call; block the prefix instead.
• Cold sales calls. Legal but unwelcome. The Telephone Preference Service tpsonline.org.uk cuts these within 28 days.
• Silent / abandoned calls. Calls that connect but don’t speak. Often a poorly-tuned auto-dialler in a legitimate UK contact centre rather than a scam. Persistent silent calls can be reported to Ofcom.

If a number checks out as a confirmed spam call

1. Don’t call back. Don’t engage. Don’t press any number to “remove yourself from the list” — that confirms a live line and gets you onto more dialler lists.
2. Block the number on your device. iOS Settings → Phone → Blocked. Android: open recent calls, tap the number, choose Block. Most UK networks also offer a my-account-level block.
3. Forward suspect texts to 7726 (spells SPAM on a phone keypad). Free on every UK network.
4. Report fraud to Action Fraud on 0300 123 2040 (England, Wales, NI) or 101 (Police Scotland). Full reporting walkthrough in our reporting a UK scam call guide.
5. Add your own report. Start a community thread tagged with the number. Helps the next person who searches the same number see a richer signal.

A worked example from today’s reports

Take the number currently topping our community spam reports: +44 345 720 3040, flagged in 1 approved spam thread. Running it through the checker pulls its Ofcom range holder, scans the public web via the AI check, and links every community thread in one view — the same three-signal verdict you’ll get for any number you paste above. Across the 4 most-reported numbers on our board right now, 75% are geographic landlines (01/02) and 25% are 03 non-geographic numbers, which is a fair picture of how UK spam campaigns spread their CLIs across number families.