Tech: What is the 24-hour SMS block? It applies when changing a SIM card—why is it necessary?
If you have ever changed your SIM card or switched to an eSIM and suddenly stopped receiving bank OTPs, you are not alone. This is neither a network glitch nor a problem with your phone. In reality, it is a security mechanism implemented by the government and the Telecom Regulatory Authority of India (TRAI).
This is a deliberately instituted system designed to protect users from dangerous cyberattacks, such as SIM swap fraud.
**What is the 24-Hour SMS Block Rule?**
Whenever a SIM replacement, SIM swap, or eSIM transfer is initiated, telecom operators temporarily block SMS services—both incoming and outgoing—for a period of 24 hours.
This is not a technical glitch, but rather a mandatory security protocol. During this period, OTPs, bank alerts, and other SMS-based services remain non-functional.
**What is SIM Swap Fraud?**
In SIM swap fraud, cybercriminals obtain a duplicate SIM card corresponding to an individual's mobile number. Once they gain control of that number, they can:
Receive bank OTPs
Log in to UPI and Net Banking accounts
Withdraw funds from the account
To mitigate this risk, the 24-hour SMS block is enforced, thereby limiting the window of opportunity available to fraudsters.
**What services are disabled during this period?**
When the SMS block is active, several digital services are affected:
UPI apps such as Google Pay, PhonePe, and Paytm cease to function
Banking transactions relying on OTP verification fail
SMS alerts (such as deposit or withdrawal notifications) are suspended
However, if your bank offers alternative options—such as email-based OTPs or hardware security tokens—these may continue to function during this period.
**What happens after 24 hours?**
Once the 24-hour period has elapsed, SMS services are automatically restored. Users do not need to adjust any additional settings to resume service. Subsequently:
You can log in to the UPI app again.
The SMS verification process is completed.
All services resume functioning normally.
What to do if you have changed your number?
If you have only swapped your SIM card, the system corrects itself automatically. However, if you have changed your mobile number entirely, you must:
Visit your bank to update your new number.
Re-set up your UPI account using the new number.
Your old UPI ID becomes inactive.
Not receiving an OTP after a SIM swap is not a technical glitch, but rather an essential security feature. While it may cause some minor inconvenience, its primary objective is to safeguard your bank account and digital data against fraud.
Disclaimer: This content has been sourced and edited from News18 Hindi. While we have made modifications for clarity and presentation, the original content belongs to its respective authors and website. We do not claim ownership of the content.
