The honest answer depends on whose number it is. Businesses want to be found, so their numbers are easy to trace. Private individuals are protected by data protection law, so their mobile numbers are not. Most frustration with "reverse lookups" comes from expecting the second to work like the first.

Business numbers

Companies, councils and charities publish their phone numbers on websites, letters and adverts. Searching the number in quotation marks usually finds the organisation. Lookup sites such as Who Rang add what callers actually wanted: a delivery, a debt collector, a survey or a sales pitch. Many business calls come from 03 or 080 numbers, which are not tied to a location, so the name matters more than the prefix.

One caution: scammers can make a call show a real company's number. If a caller claiming to be your bank asks for money or passcodes, hang up and ring the number on your card, whatever the screen said.

Private mobile numbers

There is no UK phone book for mobiles. Networks hold customer details but will not disclose them to other members of the public, and doing so would breach UK GDPR. What you can learn legally is limited to:

  • that it is a mobile number and which network the number range was allocated to;
  • whether other people have reported calls from it;
  • whether the owner has linked it to a public profile, such as a business page or a messaging app photo.

Paid sites that promise a name and address for any mobile are, at best, repackaging old marketing data. At worst, they take a fee and give you nothing you couldn't see for free.

Landline numbers

Landlines listed in the phone book can be looked up through directory enquiries services. Ex-directory numbers are not available, and more households are ex-directory than listed.

When the owner genuinely needs to be identified

If calls are threatening, abusive or part of harassment, don't try to unmask the caller yourself. Keep a log of dates and times, tell your phone provider and report it to the police. Police can request subscriber information from networks through legal processes, which is exactly what those protections are there for. The same applies to withheld numbers - see whether the police can trace no caller ID in the UK.

For everyday unknown calls, you rarely need a name at all. Checking the number's reports and type tells you whether it's safe to answer, and you can see which numbers are being checked right now on the new numbers page.