For non-US carriers (Vodafone, Airtel, Jio, EE): In 2021, most rolled out automated detection. If you receive 60+ messages in 2 minutes, the carrier temporarily throttles your inbound SMS. Verify this is active by asking customer support to enable "burst SMS protection."
In 2021, carriers partnered with apps like:
Organizations that provide SMS-based services (like OTPs) must secure their interfaces to prevent them from being exploited by attackers:
Understanding why an attack is happening helps in formulating a response.
: This is the quickest way to stop the notification noise. On most smartphones, you can set DND to allow calls and messages only from your contacts, effectively silencing the influx of anonymous "bomber" texts. Enable Built-in Spam Protection :
Apps like Pulse SMS or Textra allow regex-based blocking. You can block all messages containing “verification code” or “OTP” temporarily. On iOS, this is impossible due to sandboxing—yet another reason Android users had an edge in 2021.
These scripts exploited a weakness in online web forms. Many websites (e.g., pizza delivery services, pharmacy apps, or two-factor authentication logins) have a feature where they send a verification code via SMS to a user.