How to Tell If You've Been SIM Swapped (and What to Do)

The most common sign of a SIM swap is that your phone suddenly loses service for no reason: no calls, no texts, no data. Then you find you're locked out of your accounts. Here's how to spot the signs, what to do in the first hour and how to protect your number.

What is SIM swapping?

SIM swapping is a scam where a fraudster uses your personal data to trick your mobile operator into moving your number to a SIM they control. Europol describes it as criminals using social engineering to take control of your number (Europol: SIM swapping, a mobile phone scam).

The FBI lists three ways it happens. A criminal can pose as you and persuade your carrier, pay a carrier employee, or trick carrier staff into installing malware (FBI IC3: Criminals Increasing SIM Swap Schemes).

Once they have your number, they get your calls and texts. That includes the one-time codes banks and other services send by SMS. They use those codes to reset passwords and take over your accounts.

Signs you've been SIM swapped

• Your phone suddenly loses service. No signal, calls or texts, while people around you still have reception. Europol says to report this to your provider immediately.
• Your carrier tells you about a SIM change you didn't ask for. The FTC lists a notice that your SIM was activated on a new device as a warning sign.
• You're locked out of your accounts. Your password stops working, or you get a password reset you didn't ask for.
• Unexpected codes or reset emails arrive. That can mean someone is trying to get into your accounts.
• You see money or account changes you didn't make. Check your bank and email first.

Source for the first three: FTC: SIM Swap Scams, How to Protect Yourself.

Is it a SIM swap or just a bad signal?

Losing signal doesn't always mean fraud. Before you panic, check these:

1. Restart your phone and toggle airplane mode.
2. Check that your plan or balance is active.
3. If you're abroad, check that data roaming is on for the right line. A data-only travel eSIM can't make calls or send texts, so that's normal.
4. Ask someone nearby on the same network if they have signal.

If none of that explains it, and you can't log in anywhere, treat it as a swap and act fast. More help in our guide to fixing an eSIM that won't activate.

What to do if you've been SIM swapped

1. Contact your carrier right away. Use another phone or a landline, and use the number on your carrier's official website or your bill. Ask them to take back control of your number and block the new SIM.
2. Change your passwords. Start with your email, since it resets everything else, then your bank and social media. Do it from a device you trust.
3. Call your bank. Ask them to flag suspicious logins and transactions, and check your cards and accounts for charges you don't recognize.
4. Report it. The FBI says to report to local police and to the Internet Crime Complaint Center at ic3.gov if you're in the US. In Europe, Europol says to report to the police once your provider confirms the swap.
5. Get identity theft help. If your bank or ID numbers may be exposed, US readers can go to IdentityTheft.gov for next steps.

How to protect yourself from SIM swapping

• Add a PIN or password to your carrier account. The FTC and Europol both recommend it. Don't use birthdays or other guessable numbers, and don't share it.
• Turn on your carrier's SIM lock. Some carriers offer this. For example, Verizon has SIM Protection, which blocks unauthorized SIM or device changes, and Number Lock, which blocks transfers to another carrier (Verizon: Enable / Disable SIM Protection and Number Lock). Ask your own carrier what it offers.
• Don't rely on SMS codes. The FTC says text message verification may not stop a SIM swap. Use an authenticator app or a security key for email, banking and crypto.
• Try passkeys. They replace passwords with a cryptographic key stored on your device (Apple: About the security of passkeys).
• Keep your number private. Limit what you post online and avoid linking your phone number to sensitive accounts when you can.
• Never share personal data with callers. If someone asks for details, hang up and call your carrier on its official number.
• Don't open suspicious links. Install apps only from official stores and keep your software updated.
• Use unique passwords. A different one for every account, so one leak doesn't open them all. More in our guide to staying safe online.

Does an eSIM protect you from SIM swapping?

Partly. Here's the honest picture.

Where an eSIM helps

• Nobody can pull it out of your phone. An eSIM is built into the phone. There's no card to steal or swap into another handset. See SIM cards vs eSIM.
• A data-only travel eSIM has no number to hijack. It can't receive your bank's SMS codes. A SIM swap needs a phone number to target.
• You can keep your main number off your travel line. On a dual SIM phone, use the travel eSIM for data and leave your home line for calls and codes. See how dual SIM works.

Where an eSIM doesn't help

• The scam happens at the carrier. Fraudsters trick the operator into moving your number. That works whatever kind of SIM you use, so a PIN on your account still matters.
• Your home number is still the target. If your bank texts codes to it, a swap still lets someone receive them, even if you travel with an eSIM.
• Some plans include a number. The Bouygues Telecom plans at SimOptions come with a French +33 number. Treat it like any other number and don't use it for bank codes.

Travelling and worried about security? A data-only eSIM keeps you online for maps and messaging without exposing your main number to a new line. Your home line stays on your phone for calls and codes. For a full explanation, read what is an eSIM, and for public Wi-Fi tips, see hotel Wi-Fi safety.

Data-only plans for Europe · 10 GB, 20 GB or 50 GB · See all Europe eSIMs · Travelling elsewhere? Find your destination

FAQs

How do I know if I've been SIM swapped?

Your phone loses service for no reason and you can't log in to your accounts. You may also get a notice from your carrier about a SIM change you didn't make. Call your carrier from another phone.

Can I detect a SIM swap before I get an SMS code?

Usually not on your own. Europol notes that victims typically notice the phone has lost service. Carrier alerts and a SIM lock can help block a swap before it happens, so ask your carrier what it offers.

How do I check if someone else is using my SIM?

Watch for lost service, missing texts or calls, and account changes you didn't make. Then ask your carrier to confirm whether a new SIM or eSIM was activated on your number.

Can someone copy my phone number?

Not by copying it from your phone. A fraudster has to convince your carrier to move your number to their SIM, using personal data they've gathered about you.

Can a SIM swap happen with an eSIM?

The scam targets your number at the carrier, so the type of SIM doesn't remove the risk. An eSIM does remove the physical card. Protect your carrier account with a PIN either way.

Does a travel eSIM put my accounts at risk?

A data-only travel eSIM has no phone number, so there's nothing for a fraudster to swap on that line. Your home number and its security are what matter.

How long does a SIM swap take?

It depends on the carrier. In a legitimate swap, your old SIM stops working once the new one is activated. In a fraud, you may notice the loss of service within minutes or hours, so don't wait to call your carrier.

What should I do first if I'm a victim?

Contact your carrier to get your number back, then change your email and bank passwords and tell your bank. After that, report it to the police.