Plan requirement
| Subscription | CLASSOUND Core or CLASSOUND Pro |
A sender ID is the name or number recipients see on your text messages. Most countries require registration first.
Why registration exists
Unregistered messages are increasingly filtered or blocked outright, because sender IDs were widely abused for fraud. Registration is how networks decide your messages are legitimate.
The practical consequence: messages sent without it may never arrive, with no error to tell you.
What varies by country
- Whether registration is mandatory or optional
- How long it takes, from days to several weeks
- What proof is needed: company registration, proof you own the brand name, a description of what you will send
- Whether a text name is allowed at all, or only a number
The United Kingdom, the United Arab Emirates and the United States each have their own regime, and the US additionally requires number registration for campaign messaging.
Two countries have put a date on it. If you send messages to either, this is not something to leave until the campaign.
- Spain, from 15 September 2026. Operators block every SMS, MMS and RCS message from an unregistered alphanumeric sender ID. Numeric senders are unaffected.
- Spain has a second clock, and it is the one that catches people. If you register with the CNMC yourself, an email goes to your legal representative and they have ten working days to approve it. Miss that window and the request is rejected automatically, with nothing to appeal. Line up whoever signs before you submit, not after.
- Austria, from 1 October 2026. Only registered alphanumeric sender IDs are delivered. Long numbers and short codes are unaffected.
What the name itself has to look like
The rules are close enough to look identical and different enough to fail on. Where several countries are in play, pick a name that satisfies the strictest of them rather than one per country.
| Length | 3 to 11 characters in the United Kingdom and Spain, 11 at most in Austria. Spaces count. |
| Case | Registered exactly as you write it, in Spain and Austria. ACME and Acme are two different sender IDs. |
| Punctuation | Spain allows space, @, &, -, _, . and +. Austria allows +, /, -, _ and &. Anything else is rejected. |
| Generic names | Refused everywhere. Info, Alert, reservation and dentist are the examples the registries themselves give: the name has to identify you. |
Spain rejects a purely numeric name, a leading or trailing space, and two spaces in a row. Austria requires the name to be demonstrably linked to your company: a trademark, an abbreviation of the brand, a subsidiary. A generic word like reservation or dentist is rejected, and an application without that justification can be rejected too.
Spain drops a name you stop using. A sender ID that goes 12 consecutive months without a message is suspended automatically. If you register one for a seasonal campaign, either send something within the year or expect to register it again.
What to send us
- List the countries you will send to.
- Write the sender ID you want, exactly as it should appear on the phone.
- Describe what you will send, in a sentence: order confirmations, appointment reminders, marketing.
- Estimate the volume, roughly.
- Send us those four.
That last one matters. Requirements differ between a handful of service messages and a marketing campaign.
For Spain, add whether your organisation is established there. A Spanish organisation registers with the CNMC directly using its own digital certificate. Everyone else authorises us to do it, which takes a signed authorisation from you, so tell us early who can sign.
Austria asks for a signature too, in a different form: a Letter of Authorization from whoever owns the brand the sender ID is built on. The company details on it have to be the brand owner's, not those of anybody registering on their behalf, which is where a form filled in by an intermediary comes back. Tell us who signs at the same time as the name.
Start early. Once the request is with us, registration takes up to 30 days, and it cannot be rushed. Beginning it the week before a campaign leaves no room inside those 30 days, and the launch slips. For Spain that arithmetic leaves no room at all. From 15 September 2026 an unregistered alphanumeric sender is blocked there, and a registration begun after that date still takes up to 30 days to complete. A numeric sender still gets through, so that is the bridge while the registration runs.
Choose a recognisable name
Use the name customers know you by. An abbreviation or a legal entity they will not recognise makes your message look like spam, which defeats the purpose.
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