Spanish operators will be required to block SMS, MMS and RCS messages that use an unregistered Sender ID, known locally as an ‘alias’, which means something as familiar as seeing a company name at the top of a text message could determine whether that message is allowed through.
So, if your business communicates with customers in Spain, now is the time to check, rather than finding out when it's too late and your messages stop arriving.
What is changing?
Spain’s National Commission of Markets and Competition (CNMC) has introduced a new Alias Register covering the alphanumeric names businesses use to identify themselves when sending messages to Spanish numbers.
This is the name you might see instead of a phone number when your bank, retailer, delivery company or airline sends you a text: the Sender ID, or alias.
The new register is intended to make it possible to verify that the name appearing on a message genuinely belongs to the organisation sending it. The wider aim is to protect consumers (and brands) against brand impersonation, making messaging fraud much more difficult.
From 15th September, operators must block messages using aliases that have not been registered. Messages using a registered alias can also be blocked where they have not originated through an appropriately registered messaging provider.
Who does it affect?
Potentially any organisation sending SMS, MMS or RCS to Spanish numbers while displaying a company, brand, trading name or other alphanumeric Sender ID.
The CNMC specifically references organisations such as banks, retailers, insurers, transport operators, public bodies and other businesses using branded messaging for things like:
- delivery notifications
- appointment reminders
- customer updates
- promotions
- service messages
In other words, this isn’t limited to marketing SMS.
If a brand name forms part of how you communicate with customers in Spain, the change is relevant.
What happens if a Sender ID isn't registered?
The important distinction is that it doesn't necessarily mean the business can no longer send messages to customers in Spain.
According to the CNMC, organisations may still be able to communicate without using the unregistered alias.
What changes is the ability to continue identifying the message using that company or brand name.
For organisations where customers recognise and trust the Sender ID, that can be a significant difference.
It also creates an operational problem if teams assume existing messaging journeys will simply continue unchanged after 15th September.
Why is Spain making the change?
Anyone with a mobile phone will have undoubtedly dealt with this problem.
A text appears to come from a recognisable bank, delivery company or other trusted brand, but the sender isn't really that organisation.
By creating a register linking Sender IDs to legitimate businesses, Spain is attempting to make that kind of impersonation harder and give consumers more confidence in the name they see when a message arrives.
It's a sensible objective, but for legitimate businesses, it also means that sender identity is becoming another part of international messaging that needs to be understood before a message is sent.
International messaging isn't one-size-fits-all
The changes in Spain are a useful reminder that successful messaging depends on more than simply having a customer’s phone number.
Before a message is sent, there are several factors that can affect whether it reaches the right person in the way you expect, from the number itself and the network it sits on, to the rules that apply in the destination market.
- Is the number formatted correctly?
- Does it belong to the country you expect?
- Is it active and contactable?
- What network is it connected to?
- Are there market-specific rules affecting how that message can be sent?
- Is the Sender ID you're using accepted in that destination?
What works when sending to a UK number may not be the same as what is required when communicating with someone in Spain, or any other international market.
What should businesses sending to Spain do now?
If your organisation sends branded messages to Spanish numbers, now is the time to check:
- which Sender IDs or aliases you currently use
- whether those aliases need to be registered
- whether registration has been completed
- whether your messaging provider is ready for the new requirements
- which customer journeys could be affected if an alias is blocked
The CNMC allows alias holders to register directly, or for other entities and messaging providers to act on their behalf. Registration requires the organisation to demonstrate that the alias is connected to its brand, company name, trade name, domain or another qualifying identifier.
Businesses that haven't yet completed the process should check the CNMC's guidance and their messaging provider's requirements ahead of the 15th September 2026 deadline.
A successful message starts before you press send
The Sender ID is only one part of the journey.
But the Spanish changes reinforce a wider principle: businesses increasingly need to understand both the number they're communicating with and the conditions around communicating with it.
At Acudo, we often call this communication readiness.
Know the number. Understand the destination. Then communicate.
Otherwise, by the time a message has failed, been blocked or gone to a number that can no longer be reached, the opportunity to check first has already passed.