Withheld number ('No Caller ID') calls

Updated 2026-05-02

When a number is withheld, your handset shows 'No Caller ID', 'Private', 'Withheld', or 'Unknown'. Hospitals, GP surgeries, and some delivery couriers use this — but so do scammers and unsolicited marketers.

Why a number might be hidden

Doctors and councils often withhold numbers to protect direct lines. Scammers and silent-call marketing operations hide their numbers to avoid takedowns and reverse-lookup checks.

Handling withheld calls

If you're not expecting a medical or council call, let it go to voicemail. Genuine callers leave a message; scammers usually don't.

Red flags

  • Withheld call followed by an automated message
  • Caller refuses to identify themselves or company on request
  • Sales pitch with no postal address or company number

What to do

  1. Let withheld calls ring out to voicemail by default.
  2. Use 1471 to check the last caller (won't work if number was withheld).
  3. Block 'No Caller ID' calls in iPhone Settings → Phone → Silence Unknown Callers, or Android equivalents.

Frequently asked questions

Can I trace a withheld number?

Not as a consumer. In serious harassment cases, your network can trace via BT's Anonymous Caller Reject service or police request.