This happens when fraudsters gain customer's personal information through activities like
Phishing (fraudulent mail),Vishing (fraudulent call), Social Engineering, etc. By creating the customer's fake ID, they obtain a duplicate SIM card from mobile operator and deactivate customer's genuine SIM card. The duplicate SIM is then used by fraudsters for fraudulent transactions in the customers' (victims') account, without their knowledge.
PRECAUTIONS TO BE TAKEN TO PREVENT SIM SWAPPING
ON YOUR PHONE OR ONLINE