What Is a SIM Swap Scam? Protect Your Number in 3 Steps

A SIM swap scam is when someone convinces your mobile carrier to move your phone number to a SIM card they hold. From that moment their phone receives your calls and text messages, including the one-time codes that banks, email and social apps send to sign in or reset a password.

Checked on 4 November 2026.

How does a SIM swap scam work?

The attacker first collects details about you, often from a data breach or a phishing message: your name, number, birthday or address. They then call or visit your carrier, pretend to be you, and say their phone was lost. If the carrier agrees, your phone suddenly shows No Service or SOS only, and the attacker starts resetting your accounts with the codes sent to your number.

How do you protect your number in 3 steps?

Add a carrier account PIN or port-out lock. Call your carrier or open its app and ask for an account PIN, a number lock or a port-out PIN, so nobody can move your number without it. Names differ by carrier.

Move important accounts off text-message codes. In your email, bank and Apple Account, switch two-factor sign-in to an authenticator app, a passkey or a security key where the service offers it. Keep SMS only as a last backup.

Keep your SIM locked too. A SIM PIN stops someone who takes your physical SIM card from using it in another phone. On iPhone: Settings > Cellular > SIM PIN (pick your line first if you have two).

What should you do if your phone suddenly loses service?

If your signal disappears for no reason while others nearby have service, act quickly. Call your carrier from another phone and ask whether your SIM or number was changed. Then change the password of your main email account first, because it can reset everything else, and check your bank for new devices or transfers.

Does a VPN stop SIM swapping?

No. A SIM swap happens at your carrier, not on your internet connection, so a VPN cannot block it. A VPN protects your traffic on Wi-Fi and mobile data; the carrier PIN and app-based sign-in codes protect your number.

Frequently asked questions

What is the difference between a SIM PIN and a carrier PIN?

A SIM PIN locks the card inside your phone. A carrier PIN protects your account at the carrier, which is what stops a SIM swap.

Are eSIMs safe from SIM swapping?

An eSIM cannot be pulled out of the phone, but a carrier can still move your number to a new eSIM, so you still need the carrier PIN.

Are text-message codes useless?

No, they are better than no second step. An authenticator app or passkey is stronger because it does not depend on your phone number.

---

CasperVPN encrypts your internet connection with WireGuard, OpenVPN, IKEv2 and CasperCloak, our own protocol, on iPhone and iPad (Mac app coming). Learn more in Set a SIM PIN on iPhone in 2 minutes or Download CasperVPN →