If you have ever changed your SIM or switched to eSIM and suddenly bank OTP has stopped coming, then you are not alone. This is not a network fault nor is it a problem with your phone. Actually this is a security system which has been implemented by the government and Telecom Regulatory Authority of India (TRAI).

This is a deliberately implemented system, the purpose of which is to protect users from dangerous cyber attacks like SIM swap fraud.

What is the 24 hour SMS block rule?

Whenever a SIM replacement, SIM swap or eSIM transfer is performed, telecom companies temporarily block SMS services (both incoming and outgoing) for 24 hours.

This is not a technical fault, but a mandatory safety rule. During this period, OTP, bank messages and other SMS based services do not work.

What is SIM Swap Fraud?
In SIM swap fraud, cyber criminals get a duplicate SIM of a person’s mobile number. As soon as they have control of that number, they

• Bank can get OTP
• Can login to UPI and Net Banking
• You can withdraw money from the account
• To prevent this threat, a 24-hour SMS block is kept, due to which fraudsters have only limited time left.

What gets closed during this period?

Many digital services are affected when SMS is blocked:

• UPI apps like Google Pay, PhonePe and Paytm do not work
• Banking OTP based transactions fail
• SMS alerts (deposit/withdrawal notifications) stop
• However, if your bank has email OTP or hardware token option, they may work during this time.

What happens after 24 hours?

After completion of 24 hours SMS services are automatically restarted. The user does not need to change any additional settings.

after this:

1. UPI app can be logged in again
2. SMS verification completes
3. All services start working normally
4. What to do if you have changed your number?

If you have just changed the SIM, the system recovers automatically. But if you have changed the mobile number itself, then you should:

• You will have to go to the bank and update the new number.
• UPI will have to be setup again on the new number.
• Old UPI ID gets discontinued

OTP not coming after SIM swap is not a defect but an important security feature. This definitely causes some inconvenience, but its purpose is to keep your bank account and digital data safe from fraud.