Withheld / 'No Caller ID' calls Higher risk
A withheld or 'No Caller ID' call hides the caller's number. Some legitimate callers withhold their number (a few doctors' surgeries, or people calling from a switchboard), but a withheld number that markets to you or pressures you is a strong warning sign — and a marketing call must not withhold its number.
Just had a call? Check if it was legal →Answer a few questions and get a verdict, the right regulator to report it to, and a ready-to-send complaint.What withheld numbers are
'Withheld', 'Private' or 'No Caller ID' means the caller has hidden their Calling Line Identity. You cannot ring the number back or look it up.
Who calls from withheld numbers
- Some clinics, switchboards and internal office lines
- People who routinely withhold their number
- Nuisance marketers and scammers hiding their identity
How scammers use withheld numbers
On a live marketing call the company is legally required to display a number and identify itself — so a withheld marketing call is already breaking the rules. Never give personal or payment details to a withheld caller. If it claims to be your bank or a service you use, hang up and call them back on a trusted number.
Tip. You can make withheld calls ring silently: on many networks and handsets, 'Silence Unknown Callers' sends numberless calls straight to voicemail.
Why the number on your screen isn’t proof
The single most important thing to know about any incoming call is this: the number you see can be faked. Through a technique called “spoofing”, a caller can make almost any number appear on your display — a bank’s real 0800 line, a local landline, even your own number. So the caller ID is a hint, never proof of identity.
Ofcom now requires phone networks to block many overseas calls that fake a UK landline number, and rules to block spoofed UK mobile numbers are on the way — but gaps remain. Until then, judge a call on what it asks you to do, not on the number it shows.
What to do when one of these calls comes in
- Never share security details — passwords, PINs, one-time codes or card numbers — on a call you did not start.
- If it claims to be your bank, HMRC or a company you use, hang up and call them back on a number from your card, statement or their official website.
- Don’t be rushed. Pressure to act “right now” is the most reliable scam signal.
- If money is involved, dial 159 to reach your bank safely; call 999 if you feel in danger.
Cut future nuisance calls
- Register free with the Telephone Preference Service — it becomes unlawful for UK companies to make live marketing calls to you after 28 days.
- Turn on your network’s free call protection — BT Call Protect, Sky Talk Shield, EE Scam Guard, and the O2 / Vodafone / Three apps screen known nuisance callers before your phone rings.
Where to report a bad call
- A marketing or recorded sales call → the ICO.
- A silent or abandoned call → Ofcom.
- A scam → Action Fraud on 0300 123 2040 (Police Scotland 101).
Not sure which applies? The Cold-Call Checker works it out for you and writes the complaint.
Other kinds of number
Often legitimate
Often legitimate
Mixed
Higher risk
Premium cost
Higher risk
Higher risk
Mixed
Sources
This is general guidance about a type of phone number, not a claim about any specific number or caller, and not legal advice. Number rules and costs are current as of the date above and can change.