https://www.bleepingcomputer.com/news/security/ftc-issues-guidance-on-protecting-against-sim-swap-attacks/

The U.S. Federal Trade Commission (FTC) issued guidance on how to protect yourself from SIM swapping attacks used by scammers to take control of your phone number, to bypass SMS-based multi-factor authentication (MFA) on your account, and steal your credentials.

SIM swapping (otherwise known as SIM hijacking, SIM splitting, or SIM jacking) is a type of account takeover (ATO) fraud through which attackers get control of a target's phone numbers.