What are Flash SMS?
Flash SMS (sometimes also called Flash Messages) are a special kind of SMS. They are displayed directly on the recipient's screen without the recipient having to open them. Usually, mobile phones can neither save these messages (with exceptions) nor send them themselves. However, there are apps that allow you to send them.
Are Flash SMS still carried by the networks?
Only to a limited extent. Most mobile networks no longer carry Flash SMS (class 0 SMS) as of August 2026. Operators have largely switched the message type off or downgrade it: the message is then either not delivered at all or delivered as a regular SMS, without the typical display directly on the screen.
What this means for you:
- Whether a Flash SMS actually arrives as a flash depends on the recipient's network and cannot be predicted. Networks within the same country may behave differently.
- A positive delivery report (DLR) says nothing about the way the message is displayed. It only confirms that the message reached the device.
- We have no influence on how the networks behave and cannot guarantee the flash display for any network.
Flash SMS is therefore not a suitable basis for a use case with ongoing volume. If your process depends on messages arriving reliably, please plan with regular SMS.
What to use Flash SMS for?
Where the message type still gets through, Flash SMS are useful for emergency notifications, for example. Using this type of SMS to send advertising is not recommended. On the one hand, these kind of messaged are particularly intrusive, and on the other hand, your customers will not be able to revisit the SMS if they did not have the time to look at your offer at the time of receipt. Here, regular SMS are usually the better choice.
Sending via Webapp
To send a Flash SMS, click New message in the top left to open the Send Message dialog. In the right panel under SMS Options, enable the Send as Flash SMS toggle, then send your message as usual.
Sending via HTTP API or Mail API
Of course you can also send Flash-SMS via HTTP API and Mail API. You can find the respective parameters here:
Sender Names on Newer Devices
Please note that sender IDs for Flash SMS are no longer displayed on many new devices. Any sender ID set are replaced by these cell phones with neutral names such as "SMS", "Class 0 SMS" or simply "SMS Message".
This is a reaction of the manufacturers to phishing via SMS. Since Flash SMS messages look like a system message on many devices, this is supposed to prevent consumers from falling for scammers who misuse the sender ID to disguise their message as an official message.
Behavior on iPhones
Under certain circumstances Flash SMS can be displayed incorrectly on iPhones: here Flash SMS are received as normal SMS when the screen of the device is locked. Apple is aware of this bug, but has not fixed it yet (as of July 2021). We will make a note here when the normal reception of Flash SMS on locked iPhones is possible again.
Behavior on Android Devices
Not all Android devices display Flash SMS in the same way. However, it is likely that Android devices do not display Flash SMS in the lock screen. Instead, the message might show as a Flash SMS after unlocking the device or as a regular SMS. We have no influence on the way Flash SMS are displayed.
Delivery Failed
Please check the section "Are Flash SMS still carried by the networks?" first - in many networks the message type is simply no longer available.
If your recipients do not receive your Flash SMS, please check the article "SMS has not been received". āØ
Please also make sure you've read the sections Flash SMS on iPhones and Flash SMS on Android devices.
If you don't find a solution there that works for you, please contact our support.
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