Field guide · No. 06 · Browser · Phone · Email

Tech-support pop-ups and calls

The tell: A warning on your screen, or a call out of the blue, says your device is infected and gives you a number.

WARNING: Your computer has been locked and infected with a virus. Do not shut down or restart. Call Microsoft Support immediately on 1-800-555-0100 to avoid data loss.

Check this example

How it works

  1. A full-screen pop-up with sirens, a countdown or a “locked” screen appears in your browser. Or someone calls claiming to be from a well-known tech company.
  2. You’re told to call a number, or to let a “technician” help.
  3. The “technician” asks you to install remote-access software, then “shows” you fake errors.
  4. They charge you for an unnecessary fix, move money between your accounts to “refund” you too much, or steal your banking logins.

A variation is a surprise invoice for a subscription you never bought, with a number to call and cancel.

The tells

  • Real operating systems and browsers never show a phone number in a warning.
  • Anyone who contacts you first about a problem with your computer.
  • A request to install AnyDesk, TeamViewer or similar.
  • Payment by gift card, crypto or wire transfer.

What to do

  • Close the browser (force-quit it, or restart the device). Don’t call the number.
  • If you let someone connect: disconnect from the internet, uninstall the remote-access tool, and change your passwords from a different device.
  • If you paid, or shared banking details: contact your bank at once.
  • For a surprise invoice: check your real statements. If there’s no such charge, there’s nothing to cancel.

Where to report it

Anywhere in the world
  • Your bank or card provider. First, if money or card details are involved. Use the number on your card.
  • The platform where it happened. Use its “Report” button: the marketplace, the messaging app, the social network.
  • Your local police. If you’ve lost money, and for a reference number your bank may ask for.
  • Your national fraud or consumer-protection agency. Search for it by country; use a government address (.gov or the equivalent).
United States

Links last checked 2026-10-12.

United Kingdom
  • Forward suspicious emails to report@phishing.gov.uk — Handled by the National Cyber Security Centre.
  • Forward suspicious texts to 7726 — Free. Your mobile provider receives the report.
  • Report Fraud (England and Wales) — If you’ve lost money or been hacked. Phone 0300 123 2040.

Links last checked 2026-10-12.

Canada

Links last checked 2026-10-12.

Australia
  • Scamwatch — Run by the national consumer regulator.

Links last checked 2026-10-12.