Porting is the transfer of a phone number from one mobile provider or SIM to another. In normal use, it lets customers keep the same number when they switch carriers or replace service. The transfer is controlled by the carrier, not by the phone itself.
In cyber security, porting matters because attackers can abuse it to take over a victim’s number. If they pass carrier checks or compromise a related account, they can move the number to a SIM they control. That can redirect SMS alerts, one-time codes, and account recovery messages, making porting a key step in SIM-swapping attacks. Defenders reduce this risk with stronger identity verification, porting locks, account PINs, and by avoiding SMS as a sole authentication method for high-value accounts.