What is Flash SMS?

A Flash SMS is a message that appears immediately on the recipient’s mobile screen, without them having to open their message inbox, and then disappears for good once they dismiss it.

Flash SMS is a value-added service from some SMS providers and is commonly used for time-sensitive messages that need to catch the recipients’ attention immediately.

Emergency alerts like floods or severe weather warnings are probably the best use case. However, it is also used to send access codes as part of some authentication solutions, although not Infobip’s mobile authentication solution, because of the security concerns outlined below.

The recipient does not need to open any app or mobile phone inbox to read the message. The message is not stored in the SMS inbox or even the phone’s memory. Once the recipient has dismissed the flash SMS, it is gone forever and is unavailable to anyone who gains access to the device.

How Flash SMS works

From a technical standpoint, flash SMS is classified as class 0 under the GSM standard, while regular SMS messages are classified as class 1 or 2.

This classification (class 0) ensures the message overrides every activity on the recipient’s phone. Whatever you are doing, flash SMSs will be delivered in real time and shown directly on your lock screen.

Benefits of using Flash SMS

Flash SMS offers several advantages over traditional SMS, making it an attractive option for businesses and individuals seeking more engaging and secure communication methods. Here are some of the key benefits of Flash SMS:

  • High open and click-through rates: They appear on the recipient’s mobile phone without opening a message inbox. As soon as you look at your phone, it is there, making it a notification with an open rate of 100%.  
  • High security: Flash SMS messages are not stored in the recipient’s device’s inbox, providing an added layer of protection. This makes them ideal for transmitting sensitive information such as one-time PIN codes (OTPs), confidential details, or emergency alerts.
  • Attention-grabbing: Flash SMS messages appear on full screen on the recipient’s device, bypassing the notification center. This ensures the message is visually prominent and immediately grabs the recipient’s attention.
  • No inbox clutter: Unlike regular SMS, flash SMS messages aren’t stored in the recipient’s message history and do not clutter their inboxes.

Potential drawbacks to using Flash SMS

Even though Flash SMS is great for grabbing customers’ attention, there are some potential drawbacks, like:

  • Higher cost: Flash SMS messages are typically more expensive than regular SMS messages because of their higher delivery priority and full-screen display.
  • Can be perceived as intrusive: Flash SMS messages can be perceived as intrusive if used excessively or for non-urgent purposes

Flash SMS use cases

Flash SMS messages are also an excellent way to personalize communication, as they can be sent with a dynamic message that includes the recipient’s name or other relevant information.

They are ideal for sending urgent messages that need to be seen immediately, such as:

  • Marketing campaigns and promotions: Flash SMS messages can be used for sending reminders, notifications, discounts, and more. But you must know the messages won’t be saved on the recipient’s phones. 
  • Emergency alerts and notifications: Flash SMS messages are often used to warn people about severe weather conditions, such as hurricanes, tornados, and floods. These messages can provide important information about the location and severity of the storm, as well as instructions for how to stay safe.
  • OTPs: Flash SMS messages are not stored on the recipient’s device’s inbox, which helps to protect the OTP from unauthorized access or interception. This is crucial for safeguarding sensitive information like passwords or financial details.
  • Authentication codes: Flash SMS can be used for two-factor authentication (2FA) to display authentication codes directly on the screen.
  • Financial transactions: Financial institutions can send real-time transaction alerts and security notifications through flash SMS.

Is Flash SMS secure?

When first created, the idea was to use Flash SMS to send confidential information like PIN codes and passwords. Still, it is not secure as the Flash SMS will display on the mobile screen even when the phone is locked, along with a vibration and audible alert if one is set.

For example, anyone nearby may see the message if the phone is on a table. That is good when it warns you of a tornado heading your way, but not if it is your credit card’s new PIN code.

Flash SMS vs. push messages

Push notifications are messages sent directly to a recipient’s mobile device through a specific mobile app. Unlike Flash SMS, push notifications are not pre-configured and require the recipient to install the mobile application and enable push services.

FeatureFlash SMSPush notifications
DeliveryFull-screen notificationNotification in the notification center
Delivery priorityHighMedium
StorageNot storedStored in the notification center
Use casesUrgent notifications, one-time passwordsApp engagement, marketing campaigns


Feb 1st, 2024
5 min read

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