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SIM swap attacks: how they work and how to protect your number

A SIM swap takes your phone number without touching your phone. Here is how attackers do it, how to tell it is happening, and what actually stops it.

What is a SIM swap?

Your phone number lives with your carrier, not in your phone. A SIM swap (also called SIM hijacking or a port-out scam) is when someone gets your carrier to move that number onto a SIM card or eSIM they control, or to transfer it to another carrier entirely. From that moment, your calls and texts, including every one-time code and password reset link, go to them.

How attackers pull it off

  1. They gather your details. Name, address, date of birth, the last digits of your Social Security number and your account PIN are often available from data breaches, social media or phishing.
  2. They impersonate you. They call support or visit a store claiming a lost or broken phone, and answer the security questions with what they found.
  3. Or they go around you. Some attacks rely on a carrier employee who is tricked, rushed or paid to make the change.
  4. They move fast. With your number active on their device, they reset your email, then your exchange, bank and social accounts, before you have worked out why your phone says “No service”.

The FBI's Internet Crime Complaint Center received 1,611 SIM swapping complaints in 2021, with adjusted losses of more than $68 million.

Warning signs

  • Your phone suddenly shows “No service” or “SOS only” where it normally works.
  • You get a text or email from your carrier about a SIM change or port request you didn't make.
  • You are logged out of accounts, or get password reset emails you didn't ask for.
  • Friends tell you they got odd messages or calls from your number.

What to do if it happens

  1. Call your carrier from another phone and report an unauthorized SIM change or port-out.
  2. Secure your email first: it is the key to resetting everything else.
  3. Change passwords and remove the phone number from your bank, exchange and social accounts.
  4. Contact your bank and any exchanges to freeze withdrawals.
  5. Report it to the FBI at ic3.gov and keep a record of every call and change.

How to protect your number

Level 1: Lock what you have (free)

Switch on your carrier's protections: Verizon's Number Lock and SIM Protection, AT&T's Wireless Account Lock, or T-Mobile's SIM and port-out protection. Set a carrier PIN you use nowhere else.

Level 2: Take the number out of your logins

Use an authenticator app or passkeys instead of text-message codes, and remove your phone number as a recovery option wherever another method exists. This limits the damage if the number is ever taken.

Level 3: Move to a secure mobile service

Settings on a mass-market account still depend on that carrier's support process. A secure carrier changes the process itself. Efani, our top-ranked service, guards every account change with an 11-layer authentication protocol, holds any port-out request for a mandatory 14-day cooling-off period, and covers up to $5 million in SIM swap losses.

See every SIM swap protection option, ranked →

Your phone number deserves more than a PIN.

Efani's SAFE Plan adds 11 layers of authentication, a 14-day port-out cooling-off period and up to $5 million in SIM swap coverage. No contract, and a 60-day money-back guarantee.

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