An unknown number called: should you ring back?
A number you don't recognise rings once and cuts off, or a missed call sits on your screen from a strange international code. The instinct is to call back. Often, that is exactly what the caller is counting on.
The wangiri (one-ring) trap
Wangiri, Japanese for one ring and cut, is a scam where fraudsters auto-dial thousands of numbers, let them ring once and hang up. Curiosity makes people call back, and the return call connects to an expensive premium-rate or international line that bills you by the second while a recording keeps you holding.
Ofcom notes these missed calls often come from small or developing countries, with example dialling codes including Botswana (+267), Guinea (+224) and Guyana (+592). If a one-ring missed call shows an unfamiliar international code, do not return it.
When it might be genuine
Plenty of unknown numbers are harmless: a delivery driver, a clinic, a tradesperson, a job recruiter. The difference is usually behaviour. Genuine callers tend to ring properly, leave a voicemail, or text you.
If you are unsure, let it go to voicemail. A real caller with a real reason will leave a message or try again. Silence after a single ring is the classic wangiri signature.
How to check safely
Search the number online before doing anything, others often report nuisance numbers. Never call back a premium-rate or international number you didn't expect, and never follow a text instruction to 'call this number urgently'.
If the call claimed to be your bank or a delivery firm, contact them on a number you find independently, not the one that called you. A tool like Allociao can flag suspicious and premium-rate numbers as they come in, so you know not to ring back before you even pick up.
FAQ
Does calling back a wangiri number cost money?
Yes, that is the whole point. The return call routes to a premium-rate or costly international destination and charges accumulate while you are kept on the line.
Can simply receiving the call cost me?
No. You are only charged if you call back. Ignoring or blocking the number is free and safe.
What if it's a number from my own country?
Treat single-ring, no-voicemail calls with suspicion regardless of origin, and let unknown callers leave a message.
Sources
Related guides
UK phone prefixes to watch (and which to leave alone)
Which UK number prefixes can cost you money (070, 084, 087, 09, 118) versus free 0800 numbers you should never block. A plain-English guide.
Silent calls: when you answer and no one speaks
The phone rings, you answer, and there's dead air. Silent calls aren't a glitch — here's what they signal, why they happen and how to report them in the UK and Ireland.
'My own number is calling me': what's going on?
Your phone shows your own number as an incoming call? It's not magic or a fault — it's caller ID spoofing. Here's what's happening and how to protect yourself.
What to do after a fraudulent phone call
Step-by-step actions after a fraudulent phone call: protect your money, where to report it in the UK and Ireland, and how to stop it happening again.