The most obvious sign of a SIM swap attack is the sudden loss of cellular service—your phone may stop receiving calls or texts even though your bill is paid and your phone is in working condition. This happens because the attacker has successfully transferred your number to their own SIM card, rendering yours inactive.
Another red flag is receiving notifications about password resets or security verification codes for accounts you didn’t access. In many cases, hackers use SIM swaps to bypass two-factor authentication and take control of your email, banking, or cryptocurrency accounts. If you can’t log into your accounts or start getting alerts about unfamiliar logins, act immediately.
You may also be locked out of your phone carrier account or see fraudulent charges on your phone bill. In some cases, you’ll be contacted by your bank or email provider about suspicious activity—this could be a last chance to secure your accounts before the attacker causes further damage.
If you suspect a SIM swap, contact your carrier immediately to regain control of your number. Change all your passwords from a secure device and alert your financial institutions. Also, report the incident to the Federal Trade Commission (FTC) and consider placing a fraud alert on your credit report.
