SIM swapping

In SIM swapping an adversary steals your number and assigns it to a new SIM card in a phone they control. It is the same process you go through when you get a new phone and the mobile carrier gives you a new SIM card.

The adversary can now use your SIM card to steal further information to log in to your accounts and either enter a verification code or reset the account password using the code or link sent to the phone.