Security & Privacy

If someone takes over your phone number through a SIM swapping attack, they may be able to access your email, banking, social media, and other important accounts. Preventing this starts with locking down your mobile account, using stronger sign-in methods, and recognizing the warning signs early.

This guide explains how SIM swapping works, how to make your accounts harder to compromise, and what to do if your phone suddenly stops receiving calls or text messages.

What is SIM swapping?

SIM swapping is a type of identity theft where a scammer tricks your mobile carrier into transferring your phone number to a SIM card or eSIM they control. Once that happens, your phone number stops working on your phone, and the scammer starts receiving your calls and text messages instead.

This usually starts long before the scammer contacts your mobile carrier. They first collect personal information about you through phishing emails, fake text messages, phone calls, data breaches, or even information you share publicly online. Posing as you, they then request the transfer. The U.S. Federal Trade Commission (FTC) warns that SIM swap scams often work this way and recommends adding a PIN to your carrier account and being cautious of phishing attempts.

This is dangerous because many online accounts use your phone number to verify your identity. Once scammers control your number, they can receive your security codes, reset your passwords, and sign in to your Apple Account, email, bank, social media, shopping, cryptocurrency, and other important accounts.

In many cases, they don’t need to steal your iPhone or Android phone. They only need control of your phone number to get around text message-based security checks.

How to prevent SIM swapping on iPhone and Android

The best way to prevent SIM swapping is to make it much harder for a scammer to convince your mobile carrier to transfer your phone number. The following steps can significantly reduce your risk.

Protect your mobile carrier account

Your mobile carrier account is just as important as your email or bank account. If someone gains access to it, they may be able to request a SIM replacement, transfer your phone number, or change your account settings without ever touching your phone.

One of the best ways to protect your account is to add a carrier account PIN or passcode. If someone contacts your carrier pretending to be you, the carrier can ask for this PIN before approving important changes, such as replacing your SIM card or transferring your phone number.

A carrier account PIN is different from a SIM PIN. A SIM PIN only locks the SIM card or eSIM in your phone so it can’t be used in another device, while a carrier account PIN protects your account with your mobile carrier. It’s also different from an authenticator app or passkey, which protects your online accounts.

Choose a PIN that’s unique and difficult to guess. Don’t use your birthday, address, “1234,” or the same PIN you use for your bank card. Also protect your online carrier account with a strong, unique password. If your carrier offers two-factor authentication for your online account, turn it on for extra protection.

Finally, review your carrier account from time to time. Make sure your contact details, recovery information, and security settings are correct, and look for changes you don’t recognize. Catching suspicious activity early can stop a SIM swapping attack before it gets worse.

Turn on carrier number lock or port-out protection

Enable your mobile carrier’s built-in account protection to stop someone from transferring your number to another SIM card or carrier without your permission.

Every carrier uses different names for these protections. You may see them called Number Lock, SIM Protection, Port-Out Protection, Account Lock, or Account Takeover Protection. The exact features and where you find them vary by carrier.

If your carrier offers one of these features, turn it on as soon as you can. You can usually find it in your carrier’s app or online account. If you’re not sure where to find it, contact customer support.

Use extra identity verification if your carrier offers it

Blocking phone number transfers is only one part of protecting your account. Some carriers also let you add extra identity checks before they approve sensitive account changes, such as replacing your SIM card or transferring your phone number.

Depending on your carrier, this can include entering a one-time verification code, answering security questions, confirming your identity in the carrier’s app, or showing a government-issued ID in a store. These extra checks stand in the way of anyone trying to pretend to be you, even if they already know some of your personal information.

If your carrier offers additional identity verification, enable it. The more ways your carrier can confirm it’s really you, the harder it is for a scammer to take over your phone number.

Watch out for phishing and social engineering attempts

Many SIM swapping attacks begin with a scam designed to steal your personal information. You may receive a fake email, text message, or phone call that looks like it came from your mobile carrier, Apple, your bank, or another company you trust. The goal is to trick you into sharing passwords, verification codes, or other details a scammer can use to impersonate you.

Be careful with unexpected messages asking you to click a link, download a file, or confirm personal information. If you’re unsure whether a message is genuine, contact the company using its official website, app, or customer service number instead of replying directly.

Be careful with the personal information you share

Scammers don’t always need to trick you directly. They may gather information from your social media profiles, public records, or data breaches to build a picture of who you are before attempting a SIM swap.

Avoid sharing personal details publicly unless they’re necessary. Be especially careful with details such as your full date of birth, home address, phone number, or answers to common security questions. Even small pieces of information can give a scammer enough to convince your mobile carrier that they’re really you.

Act immediately if your phone loses service

One of the first signs of a SIM swapping attack is suddenly losing mobile service. If your phone shows “No Service” or “SOS” and restarting it doesn’t fix the problem, don’t ignore it. Your phone number may have been transferred to another SIM card without your permission.

Contact your mobile carrier immediately and ask whether any recent changes have been made to your account. If you didn’t request a SIM replacement or phone number transfer, ask the carrier to freeze your account and restore your number. Then check your email, banking, social media, and other important accounts for suspicious activity, and change your passwords from a trusted device if you think your accounts have been compromised.

Warning signs of a SIM swap attack

A SIM swap attack often starts with changes to your phone service before you notice problems with your online accounts. If you spot these warning signs and act quickly, you may be able to stop scammers before they take over your accounts.

Watch out for these common signs:

• You suddenly lose mobile service: Your phone shows “No Service” or “SOS” even though you’re in an area with good coverage.
• You stop receiving calls or text messages: Friends, family, or colleagues say they’ve been trying to reach you, but your phone isn’t receiving calls or messages.
• You receive unexpected password reset emails or login alerts: You see password reset requests, one-time verification codes, or sign-in alerts that you didn’t trigger.
• Your carrier notifies you about SIM or account changes: You get an email or text confirming a SIM replacement, eSIM activation, phone number transfer, or account update that you didn’t request.
• You notice unusual activity on your accounts: You find unfamiliar bank transactions, password changes, new devices signed in to your accounts, or emails and social media activity that weren’t yours.

What to do if your number is SIM swapped

If you think your phone number has been SIM swapped, act immediately. The faster you respond, the better your chances of stopping scammers from accessing your accounts and limiting any damage.

Take these steps as soon as possible:

• Contact your mobile carrier: Ask for the fraud or account security department and tell them you believe your phone number has been SIM swapped. Ask them to suspend the unauthorized SIM, restore your number, and add a PIN or other available protections.
• Regain control of your phone number: Work with your carrier to transfer your number back to your SIM card or eSIM and confirm that no unauthorized changes remain on your account.
• Change passwords for your important accounts: Start with your email account, then update passwords for your banking, mobile carrier, social media, shopping, and other sensitive accounts. Use strong, unique passwords for each one.
• Replace SMS verification with stronger authentication: If your accounts support it, switch from text message verification to an authenticator app, passkeys, or a physical security key. This makes it much harder for someone to access your accounts through your phone number.
• Check your financial accounts for suspicious activity: Review your bank, credit card, and payment accounts for transactions you don’t recognize. Report any unauthorized activity immediately and follow your financial institution’s fraud procedures.
• Report identity theft or fraud if necessary: If someone accessed your accounts or stole your personal information, report the incident to the appropriate authorities and keep records of any fraudulent activity and communications with your carrier.

How to protect the devices and accounts tied to your phone number

A SIM swap attack doesn’t stop with your phone number. Once scammers take control of your number, they’ll often try to access your email, Apple Account, banking apps, password manager, social media, and any other account that uses your phone number for verification. Protecting these accounts can limit the damage, even if your number is compromised.

Here are a few simple ways to better protect your devices and accounts:

• Lock down your email first: Your email account is often the key to your other accounts because it can be used to reset passwords. Protect it with a strong, unique password and use an authenticator app, passkeys, or a security key instead of SMS verification whenever possible.
• Guard your Apple Account and password manager: These accounts often contain sensitive information and can be used to access other services. Make sure they use strong authentication methods that don’t rely on your phone number alone.
• Secure your banking and mobile carrier accounts: Add an account PIN or passcode where available, and regularly review your account settings for any unauthorized changes.
• Watch out for phishing attempts: Many SIM swap attacks begin with phishing emails, fake text messages, or phone calls designed to steal your personal information or account credentials. In fact, the World Economic Forum’s 2026 Global Cybersecurity Outlook found that 77% of organizations reported an increase in cyber-enabled fraud and phishing. Be cautious of unexpected messages asking you to click links, download files, or share verification codes.
• Be careful what you download: Malicious apps and files can steal passwords or other information that helps scammers take over your accounts. Only download software from trusted sources and keep your devices up to date.
• Scan your Mac if something doesn’t seem right: If you’ve clicked a suspicious link, downloaded an unknown file, or your browser suddenly starts redirecting you to unfamiliar websites, it’s worth running a malware scan. A security solution like Intego can detect malicious files, unwanted software, and other threats that could put your accounts at risk. While it can’t prevent SIM swapping itself, it can protect the Mac you use to access your most important accounts.

Stay one step ahead of SIM swapping

SIM swapping can happen to anyone, but there are practical steps you can take to reduce your risk. Protecting your mobile carrier account, using stronger sign-in methods, and watching for warning signs can leave a scammer far fewer ways to take over your phone number.

The most important thing is to act before you’re targeted. A few minutes spent improving your account security today can save you from losing access to your key accounts later.

Frequently asked questions

Does a SIM PIN prevent SIM swapping?

No. A SIM PIN only locks the SIM card or eSIM in your phone so it can’t be used in another device. It doesn’t stop a scammer from convincing your mobile carrier to transfer your phone number to another SIM card or eSIM. For better protection, add a carrier account PIN, enable port-out or SIM protection, and use an authenticator app or passkeys instead of SMS verification.

How do I prevent SIM swapping on iPhone?

You can’t completely prevent SIM swapping on an iPhone because the attack happens at your mobile carrier, not on your device. To reduce your risk, add a PIN or passcode to your carrier account, enable SIM swap or port-out protection if your carrier offers it, and use an authenticator app or passkeys instead of SMS verification. You can also turn on a SIM PIN to prevent unauthorized use of the SIM card or eSIM itself.

Does eSIM prevent SIM swapping?

No. An eSIM doesn’t prevent SIM swapping. A scammer can still trick your mobile carrier into transferring your phone number to an eSIM they control. To reduce your risk, add a PIN to your carrier account, enable SIM swap or port-out protection if available, and use an authenticator app or passkeys instead of SMS verification.

What is port-out protection?

Port-out protection is a security feature offered by some mobile carriers that blocks unauthorized transfers of your phone number to another SIM card or carrier. When it’s enabled, your carrier requires additional verification before approving a transfer, which stops most SIM swap attempts before a transfer goes through.

What should I do if my phone suddenly has no service?

If your phone suddenly loses service and restarting it doesn’t help, contact your mobile carrier immediately. Your phone number may have been transferred without your permission. Also check your email and other important accounts for suspicious activity, and change your passwords if you think your accounts may have been compromised.

About Doris Muthuri