Flash SMS, also known as Flash Message or Class 0 SMS, is a special type of SMS that is displayed directly on the recipient's mobile phone screen. Unlike regular SMS messages that get stored in the recipient's inbox, Flash SMS does not get saved and disappears once the recipient dismisses or exits the message.

The main characteristics of Flash SMS include:

Immediate Display: When a Flash SMS is received, it is immediately displayed on the recipient's screen, often with a pop-up or full-screen notification, ensuring that the message is seen promptly.

No Inbox Storage: Flash SMS messages are not saved in the recipient's inbox, making them ideal for conveying urgent or critical information without cluttering the message storage.

No User Interaction Required: The message is automatically displayed without requiring any action from the recipient. However, the recipient can dismiss or exit the message at any time.

Flash SMS is commonly used for time-sensitive or important notifications, alerts, emergency messages, two-factor authentication (2FA) codes, and messages that require immediate attention. Examples of use cases include banking transaction alerts, security alerts, appointment reminders, and critical system notifications.

However, it's important to use Flash SMS judiciously, considering its intrusive nature and the potential to disrupt the user's current activity. Regulations and guidelines regarding the use of Flash SMS may vary by region and should be followed to ensure compliance and optimal user experience.

Understanding Flash SMS and its appropriate use cases is crucial for businesses and organizations to effectively utilize this communication tool, ensuring that important messages are promptly delivered and acknowledged by the recipients.