A type of identity theft whereby the crook has already stolen a user's login data to a financial account but needs to verify actually logging in via the code commonly texted to a phone number. See
two-factor authentication and
SIM card.
By gathering personal data on social media or via a phishing email, SIM swappers identify themselves to the phone carrier as customers who have a damaged or stolen SIM card. If the carrier accepts the fake story, it will switch the phone number to the new SIM card, and the hijacker will receive regular text messages and phone calls.