Illegal SIM swaps allow fraudsters to hijack a target’s phones number and use it to steal financial data, passwords and other items of value. Phone numbers stink for security and authentication, but most of us have so much invested in these digits that theyve become de facto identities. When you get new numbers, they are recycled from previous owners because there arent any new ones anymore. Many major providers still let people reset their passwords with just a text message.”]
Source: https://krebsonsecurity.com/2019/03/why-phone-numbers-stink-as-identity-proof/