SIM swap
Fraudulently transferring your mobile number to a SIM card the attacker controls, so they can intercept your calls, texts, and one-time passcodes.
Also known as: SIM hijacking, SIM porting fraud
Last reviewed: 1 June 2026
A SIM swap (or SIM hijack) involves a fraudster convincing your mobile network to reassign your phone number to a new SIM they hold. This is typically done by impersonating you to customer services, using personal data gathered from social media, data breaches, or phishing.
Once they control your number, all SMS messages — including one-time passcodes used for two-factor authentication on your bank, email, or crypto accounts — are delivered to the attacker rather than you. You will notice your phone losing signal and being unable to make calls or receive texts.
SIM swaps are commonly used as a stepping stone to account takeover, particularly for bank accounts and cryptocurrency exchanges that rely on SMS-based 2FA. Using an authenticator app rather than SMS for 2FA significantly reduces this risk.