SIM swap
Plain definition. A SIM swap is when criminals trick a phone company into moving a victim’s number to a SIM card they control, to break into digital currency accounts.
Technical definition. The FBI’s San Francisco Division describes SIM swapping as criminals socially engineering a mobile phone company’s customer service representative to port the victim’s phone number to a SIM card and phone the attackers control, with the aim of gaining access to the victim’s digital currency accounts. With the number in hand, attackers start password resets on email, cloud storage and social media accounts, since these resets usually arrive by text message to the victim’s number. They also defeat SMS-based or mobile application-based two-factor authentication, then move the digital currency into accounts they control.
On this site
On this site, SIM swap comes up in Can someone steal my crypto through my phone number (SIM swap)? and How do I secure my account on a crypto trading platform (security keys, withdrawal allowlists, alerts)?.
Source
FBI San Francisco Warns the Public of the Dangers of SIM Swapping — FBI (fbi.gov), read October 1, 2026.