SIM Swap: Why do bank OTPs stop working the moment a new SIM is inserted? Is it a network issue, or something else?

Why Bank OTPs Stop After Getting a New SIM: When we acquire a new SIM card, replace an old one, or switch from a physical SIM to an eSIM, a peculiar issue often arises. Suddenly, our bank alerts, UPI app activations, and—most importantly—Net Banking OTPs (One Time Passwords) stop arriving completely. People often become distressed, assuming this is due to a network glitch or a failure in SIM activation; some even go so far as to call customer care. Many are unaware that this is, in fact, a deliberately designed government security mechanism intended to safeguard your bank account.

What is the 24-Hour SMS Block Rule, and Why is it Necessary?
According to the mandatory regulations set by TRAI—the Telecom Regulatory Authority of India—the moment a user completes the process of a SIM replacement, SIM swap, or eSIM transfer, telecom operators are required to completely block both incoming and outgoing SMS services for that specific number for the subsequent 24 hours. The sole objective behind enforcing this strict rule is to protect customers from dangerous fraudulent activities, such as SIM Swap Fraud (or eSIM Swap Fraud).

How Does SIM Swap Fraud Work?
In this scheme, cybercriminals misuse another person's identity documents or deceive the telecom operator to procure a duplicate SIM card for that individual's phone number. As soon as the duplicate SIM is activated in the criminal's possession, the original user's phone loses its network connectivity. Subsequently, the criminals can easily intercept the bank OTPs and alerts directed to that number, misuse them, bypass banking authentication protocols, and completely drain the entire bank account.

TRAI's 24-hour SMS block rule aims to neutralize precisely this type of fraud. Thanks to this regulation, even if a fraudster succeeds in obtaining a duplicate SIM card for your number, they will be unable to receive any SMS messages or OTPs on it for the following 24 hours. This provides the genuine user with a substantial window of time to detect any fraudulent activity and have their mobile number and bank account blocked, thereby reducing the scope for misuse to a negligible level. Once this 24-hour timeframe elapses, your SMS services are automatically restored without requiring any further action on your part.

**What services will not function during this period?**
While this SMS block remains active on your number, several of your digital and banking services—such as UPI applications like Google Pay and PhonePe—will be directly affected. These digital payment apps typically verify your identity by sending a silent background SMS from your device during the login or reactivation process. During this blocking period, you will be unable to either log in to these apps or reactivate them.

Furthermore, any online transaction involving internet banking or a debit card that relies entirely on a mobile OTP for authentication cannot be completed during this time. Additionally, you will not receive routine text messages (alerts) regarding debits or credits to your bank account during this period.

**What to do after the block is lifted?**
As soon as the 24-hour period following SIM activation is complete, you do not need to take any separate action. Simply reopen your UPI app and initiate the verification process as you normally would. The app will verify your mobile number by automatically sending an SMS from your device, and all your digital payment services will be instantly restored to their previous operational state.

**Under what circumstances would a different procedure apply?**
Please note that the information outlined above applies only in cases involving a simple SIM replacement or swap. If, however, you have acquired a completely new mobile number and wish to link it to your bank account, the procedure will be slightly more involved:

First, you must visit your respective bank branch to register or update your new mobile number by submitting a KYC (Know Your Customer) form.
Once your mobile number has been successfully updated in the bank's records, you will need to register your UPI ID afresh using this new mobile number.

As soon as the new mobile number becomes active, your previous UPI ID—which was linked to your old number—will permanently cease to function.

Disclaimer: This content has been sourced and edited from Amar Ujala. 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.