What is Flash SMS?

A high-priority text message that appears directly on a recipient's phone screen as a pop-up without being stored in the inbox, used for urgent alerts and OTPs.

Flash SMS (also known as Class 0 SMS) uses a special message class that instructs the recipient's device to display the content immediately as a full-screen overlay or pop-up, bypassing the standard inbox. Because the message does not remain saved on the device by default, it is ideal for sensitive information like OTPs, bank PINs, and emergency alerts where message persistence is a security risk. Flash SMS is supported by all GSM networks and most mobile devices. It is classified as transactional and can bypass DND restrictions when used for account security purposes. Businesses in banking and fintech frequently use flash SMS for OTP delivery to enhance security and user experience.

Frequently Asked Questions

Compliance

Does Flash SMS get saved in the recipient's inbox?

No. Flash SMS messages are displayed as immediate pop-ups and are not automatically saved to the device's SMS inbox. Some devices may allow the user to manually save the message, but by default it disappears after viewing.

Speed

Is Flash SMS more secure than standard SMS for OTPs?

Flash SMS offers a minor security advantage for OTPs since the code is not stored in the inbox and is less likely to be intercepted by other apps with SMS read access. However, the core security of the OTP depends on the generation and validation logic, not the delivery class.

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Related Terms

Promotional SMS OTP DND Bulk SMS Sender ID SMS Gateway Priority Route TRAI 2FA

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