A flash SMS is a type of text message that - without user action - appears directly and fullscreen on the the mobile phone. Flash SMS is useful in case of emergencies or if you want to send confidential information, such as a One Time Password.
You can send flash SMS through our API and via SMPP. It's not possible to send flash SMS via our webinterface.
Benefits of flash SMS:
Users can't ignore your message because it appears fullscreen and the user actively needs to close it.
It's safer than standard SMS, because the message isn't stored in the inbox.
In case flash SMS isn't supported by an operator or mobile phone, the message is still sent as a standard SMS