Persuading or bribing a mobile operator to transfer a victim’s phone number to an attacker-controlled SIM, capturing SMS codes and account recovery.
Why it matters
It is why SMS is the weakest second factor: the “something you have” is a number a third party can reassign. App-based authenticators and hardware security keys are not transferable this way.
Not advice. Definitions are for understanding, not instruction. Nothing here is financial, legal, tax or security advice.