SIM swap
A takeover of your phone number: someone gets your mobile carrier to move it to a SIM card they hold, and from then on your calls and texts, login codes included, go to them.
The swap happens at the carrier, not on your phone. According to the FBI, criminals do it by posing as you to the carrier’s staff, by paying an employee, or by tricking employees into installing malware that lets the criminals make the swap themselves. The FBI advises watching for any change in how your phone gets text messages.
It matters because a phone number often unlocks everything else. Whoever gets your texts can ask your email and other accounts for a password reset, receive the codes, and take the accounts over, an exchange account included. A key that lives only on your device doesn’t move with the number; anything that trusts a text message does.
The FBI received 1,611 complaints about SIM swaps in 2021, with more than 68 million dollars lost. In 2025 there were 971, with 17.4 million dollars lost; 121 of them involved crypto. In January 2024, someone took over the US Securities and Exchange Commission’s account on X through a SIM swap, and posted a fake announcement that bitcoin ETFs had been approved. The man who carried out the swap, posing as the number’s owner with a fake ID he had printed, pleaded guilty in February 2025 and was sentenced to 14 months in May.
To protect yourself, take your phone number out of anything that holds money: use an authenticator app, a passkey or a security key instead of text messages, and ask your carrier for a PIN or a lock on moving your number. The guide on losing your phone goes further, and phishing is often how the swappers get the details they need.