SIM-swap is a form of fraud that allows crooks to bypass SMS-based two-factor authentication (2FA) and crack online banking or other high-value accounts. Many carriers don t ask in-depth security questions that fully verify that the caller is in fact the legitimate cell phone user. Princeton University researchers tested five North American prepaid telecom companies to see if they could successfully port their own number to another SIM card. In trying 10 times each with each carrier, they found that they could do so in most cases, thanks to a lack of strong verification processes.
Source: https://threatpost.com/mobile-customer-service-sim-swap-fraud/151993/