What Is SIM Swapping and How Can You Protect Your Number?

Imagine your phone suddenly loses network service. You assume it's a temporary outage, but someone may have transferred your number to a SIM card they control.

This type of fraud is called SIM swapping. Criminals can use a stolen phone number to intercept text messages and attempt to access accounts protected by SMS verification.

Here's how it works and how you can protect yourself.

What Is SIM Swapping?

SIM swapping happens when a criminal tricks a mobile network provider into transferring your phone number to a SIM card or eSIM they control.

Once the transfer succeeds, your phone may lose service, while the criminal receives calls and text messages intended for you. If your accounts rely on SMS verification, this can make account takeover easier.

3 Warning Signs to Watch For

• Sudden loss of mobile service: Your phone unexpectedly shows “No Service” or cannot make calls or send texts, even where coverage is normally available.

• Unexpected security codes: You receive verification codes or password-reset alerts you didn't request.

• Unfamiliar account activity: You notice login alerts, password changes or transactions you didn't authorise.

A network outage can also cause a loss of signal, so one sign alone does not prove a SIM swap. However, unexpected loss of service deserves prompt attention.

4 Ways to Protect Your Number

1. Secure your mobile-provider account

Ask your telecom provider whether it offers an account PIN, additional identity verification or protection against unauthorised SIM replacements.

2. Avoid relying only on SMS verification

Where possible, protect your email, banking and social media accounts with an authenticator app or security key instead of SMS codes.

3. Keep personal information private

Avoid sharing sensitive personal details publicly. Never disclose verification codes or account credentials to someone who contacts you unexpectedly.

4. Use strong, unique passwords

Protect your email account especially carefully. It can be used to reset passwords for many other services.

What If You Suspect a SIM Swap?

Act immediately:

1. Contact your mobile provider from another phone and ask it to secure your number and reverse any unauthorised SIM change.

2. Contact your bank if financial accounts or transactions may be affected.

3. Secure your email and other important accounts using a trusted connection.

4. Report suspected financial cyber fraud in India through cybercrime.gov.in or call 1930.

The Bottom Line

SIM swapping can put your phone number and accounts at risk, but a few precautions can make an attack harder.

Secure your telecom account, use stronger authentication and never ignore an unexplained loss of mobile service.

Sources: U.S. Federal Trade Commission — SIM Swap Scams · Federal Communications Commission — SIM-Swap and Port-Out Fraud

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