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Attacks

What is Caller ID Spoofing?

The practice of falsifying the phone number displayed on a recipient's caller ID to disguise the caller's identity — used by scammers to impersonate banks, government agencies, and known contacts to trick victims into answering and sharing information.

Also known as: Phone Number Spoofing, Fake Caller ID, Number Spoofing

When your phone shows a call from your bank, the IRS, or even your own number — it might be a scammer. Caller ID spoofing is trivially easy and makes phone-based scams extremely effective.

How It Works

  • VoIP (Voice over IP) services allow callers to set any phone number as their outgoing caller ID
  • Spoofing services are available for as little as $1/month
  • The spoofed number can be:
    • Your bank's real customer service number
    • A government agency (IRS, SSA, police)
    • A local number in your area code (to increase answer rates)
    • Your own phone number (to confuse you into answering)
    • A contact in your phone (to exploit trust)

Common Spoofing Scams

Bank Fraud

  • "Your account has been compromised" — asks for account numbers, PINs, or one-time codes
  • Caller ID shows your actual bank's number
  • The scammer may already have partial information from a data breach

Government Impersonation

  • Fake IRS calls threatening arrest for unpaid taxes
  • Social Security Administration claiming your SSN has been "suspended"
  • These scams collect $29+ million per year from US victims

Tech Support

  • "Microsoft" or "Apple" calling about a virus on your computer
  • Aims to get remote access to your device or payment for fake services

Neighbor Spoofing

  • Using a number with your same area code and prefix
  • Makes the call appear local, dramatically increasing answer rates

Why It's Hard to Stop

  • STIR/SHAKEN protocol (mandated by FCC in 2021) authenticates caller ID on some networks, but adoption is incomplete
  • International calls can bypass US authentication systems
  • VoIP makes it trivially cheap to generate millions of spoofed calls
  • Robocall technology can make thousands of spoofed calls simultaneously

How to Protect Yourself

  1. Never trust caller ID alone — if your "bank" calls, hang up and call the number on your card
  2. Don't share sensitive information on incoming calls — legitimate organizations won't ask for passwords or PINs by phone
  3. Use call-blocking apps — Nomorobo, Hiya, or your carrier's spam filter
  4. Register on the Do Not Call list (donotcall.gov) — reduces legitimate telemarketing but not scam calls
  5. Let unknown calls go to voicemail — scammers rarely leave messages
  6. Report spoofed calls to the FCC at fcc.gov/consumers/guides/spoofing-and-caller-id

Related Terms

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