Phone calls
What to do if your SIM suddenly stops working
No network can mean someone else is receiving your OTPs. Call the operator from another phone, then call the bank.
A SIM swap moves your phone number onto a SIM you do not have. Your phone shows no signal. OTPs from the bank, email, and WhatsApp go to someone else. It often follows a call that asked for an OTP to update KYC, replace a SIM, or port the number.
Do this in order
Use another phone. Call your mobile operator and say the number has lost network and you did not request a new SIM. Ask them to block the change and issue a replacement only to you, in person, with your ID.
Call your bank from the number on your card. Tell them your SIM may have been swapped and ask them to watch or freeze UPI, cards, and new payees.
After you have the number back, change email and banking passwords. Turn on an authenticator app so the next OTP is not only an SMS.
Call 1930 if any payment already left, or if a new account was opened with your documents.
Do not share OTPs for SIM replacement, porting, or KYC. The operator already has ways to identify you in a store. A code read out on a call is what completes the swap.
If money has already left your account, call 1930 or report at cybercrime.gov.in. This page is awareness information. It does not file a complaint.