What is a flash SMS and when should your company use it

A flash SMS is a text message that appears immediately on the phone screen, without the person opening their inbox, and that is not saved automatically. It is a useful tool for urgent messages, but not for everything.

What a flash SMS is

Technically, a flash SMS is a class 0 message. The message class is set in a field of the SMS itself, the Data Coding Scheme (DCS), defined in the 3GPP TS 23.038 technical specification.

For class 0, the specification says the message is shown to the user immediately and is not stored automatically on the SIM card or in the phone memory. That is why it is also called an “instant” or “display” message.

What the user sees

When it arrives, the message appears on top of whatever the person is using. They usually have to dismiss it to continue.

The exact display depends on the brand, model and operating system. Some phones offer to save it; others discard it when it is closed. Treat it as a read-now notice, not as a record the customer can check later.

Flash SMS vs. regular SMS

• Visibility: a flash SMS pops up on screen; a regular one arrives in the inbox with a notification.
• Persistence: a flash SMS is not saved automatically; a regular one stays in the history.
• Later reference: with a flash SMS the customer may lose the data after closing it; with a regular one they can read it again.
• Best use: flash for urgent, single-use content; regular for almost everything else.

When to use it

1. One-time codes for immediate use: the code appears without searching for it and is not kept in the phone history.
2. Security alerts: a login attempt or a transaction the customer must confirm or reject right now.
3. Critical operational notices: a service outage, a branch closure or an urgent change for field staff.
4. Internal emergencies: short instructions for on-call or response teams.

When not to use it

Avoid flash SMS for promotions, coupons or anything the customer will want to keep: it interrupts what they are doing and can feel intrusive. It is also a poor fit for data the customer will need later, such as an order number or an address.

If the message includes a link, keep in mind that not every phone lets the user open it from the pop-up. A regular SMS works better in those cases.

Best practices

• Keep messages very short: the customer should get it at a glance.
• Always identify your brand in the sender or at the start of the text.
• If the data matters, also send a regular SMS or keep the record in your app.
• Track delivery reports as with any other SMS.
• Test it on different devices before using it at scale.

On the Grupo Tecnophone platform, flash SMS is available as a sending option, both from the dashboard and through the API.

See also: SMS for government and institutions

Sources

• ETSI TS 123 038 V10.0.0 (3GPP TS 23.038), “Alphabets and language-specific information”, section 4: Data Coding Scheme, class 0. etsi.org
• Wikipedia, “Data Coding Scheme” (accessed September 2026). wikipedia.org

Frequently asked questions