A SIM swap moves your mobile number to a SIM the fraudster controls. From that moment every OTP, every bank call and every ‘forgot password’ code goes to them. It is the step that turns a leaked password into an emptied account.
How it happens
The fraudster collects your details from a leak or a phishing form, then either convinces the operator's store to issue a ‘replacement’ SIM with a fake ID, or calls you as the operator offering a ‘free 5G upgrade’ and gets you to forward a 20-digit SIM number or dial a code.
Your phone loses signal. Within minutes the new SIM is active and your OTPs are theirs.
The early signs
No network for more than a few minutes in a place where you normally have signal; an SMS about a SIM change or ‘upgrade request’ you did not make; friends saying your number is unreachable; a bank alert for a login you did not do.
What stops it
Ask your operator to add a SIM-change PIN / verbal password to your account. Never read out a SIM number or dial a code a caller gives you. Use an authenticator app or passkeys instead of SMS OTP wherever the service allows. Keep the number you use for banking off social media and marketplace listings.
If it has already happened
From another phone, call the operator and block the new SIM; call your bank's official number and freeze cards, UPI and net banking; change passwords for e-mail and banking from a trusted device; report at cybercrime.gov.in and keep the acknowledgement for the bank.
Checklist
- ☐SIM-change PIN / verbal password set with the operator
- ☐Authenticator app or passkey enabled on e-mail and banking
- ☐Banking number not published on listings or social profiles
- ☐Operator's official app installed (it shows SIM-change requests)
- ☐Bank's official helpline saved from the card / passbook
- ☐Family knows: ‘no signal + bank alert’ means call the bank first
Where to report
- • 1930 — national cyber-crime helpline (money lost: call within the first hour)
- • cybercrime.gov.in — National Cyber Crime Reporting Portal
- • chakshu.sancharsaathi.gov.in — report fraud numbers and SMS
- • sachet.rbi.org.in — RBI complaints about unregistered lenders / deposit schemes