Spain
To send SMS and RCS to Spanish numbers with an alphanumeric sender, the alias must be registered with the CNMC. How the registration works, the two ways to do it, and the alias rules.
To send SMS to Spanish numbers with an alphanumeric sender, that sender must be registered with the CNMC (Comisión Nacional de los Mercados y la Competencia), in its Sender Alias Registry. Registration is equally mandatory for RCS, as an alias independent of the SMS one — registering one does not include the other. In Instasent, the CNMC process for RCS will switch on when the RCS channel launches — see Does it apply to RCS too?.
How registration works
Registration has two parts, and each one is done by a different person: the alias details are provided (the brand, the owner, the legal representative) and then the legal representative authorises the alias at the CNMC. The CNMC always notifies the legal representative, so their details have to be correct.
How to register your alias: two paths
You can register the alias in two ways, and both end with the legal representative authorising it at the CNMC's electronic office:
You provide the details in Instasent, Instasent files the alias in the CNMC Registry as the provider, and your legal representative only has to authorise it when they receive the CNMC's notification.
You register it yourselfYou submit the request yourself at the CNMC's electronic office. It's the fastest route: the decision usually comes through ahead of the bulk filing a provider does.
What you provide
The details aren't all asked at once, or in the same place: the legal profile holds who you are, and whatever the CNMC additionally requires is asked when you file.
On the legal profile (Settings → Organization → Legal Profiles), creating one asks for two things:
- Brand details — the alias and the brand it represents.
- Brand owner — the company or person legally responsible for the alias.
What the regulator requires comes later, in a second sheet called Details for the regulator, which appears inside the sender request once you pick a filing option:
- Legal representative — the person who authorises the alias at the CNMC. The CNMC notifies this email, so it must be correct and reachable.
- Third parties (optional) — intermediary agencies or related companies.
- The brand owner's registered address, if you haven't set it yet.
You can also do it ahead of time, without waiting to request anything: open the profile under Legal Profiles and click Add (or Edit) on its regulator card.
The Filing step in the sender request
Spain adds one extra field to the country request you submit on the sender (the generic flow is in SMS senders & registration). When you request Spain, the form shows a Filing choice for the CNMC:
- I'll file it myself — the recommended option, and the one selected by default. Pick it if you've already registered the alias with the CNMC yourself (see Registering your alias directly), and supply the proof.
- Instasent files for you — Instasent submits the alias to the CNMC registry on your behalf. Your legal representative still has to authorise it at the CNMC (see Authorising the alias at the CNMC).
The sender request also shows a card titled Spain · CNMC with the notice: This country is regulated by CNMC, which will require every sender to be registered from 15 September 2026. After that, operators block messages from senders without a valid registration. Completing this step registers yours ahead of time.
How long it takes
Plan for some lead time: once the alias is submitted to the CNMC, a decision can take up to a month. And if the CNMC doesn't respond within that window, the request is treated as denied (negative administrative silence) and has to be filed again from scratch. So request your sender with time to spare, and double-check that your legal representative's details are correct before submitting, to avoid losing that month.
Registering yourself directly is usually quicker than waiting for the bulk filing a provider does, so if you're in a hurry, consider self-registration.
If the CNMC rejects the registration, the rejection reason tells you what to do: sometimes filing again is enough, sometimes you need a different alias — see Alias rejected by the CNMC.
Alias rules
| Length | 3 to 11 characters |
| Allowed | letters a–z and A–Z, digits 0–9, and @ & - _ . + |
| Not allowed | numbers only, accented characters (á, é, í…), the symbols ! ? # % * € ( ) [ ], and generic names ("Banco", "Mensaje", "Urgente") |
The alias must be genuinely and legitimately tied to your brand. The CNMC may reject one that is generic or that could cause confusion, fraud or impersonation.
Does it apply to RCS too?
Yes. Registration with the CNMC is also mandatory for RCS, and it's a registration independent of the SMS one: the SMS alias and the RCS alias are registered separately, and registering one does not include the other. The CNMC portal already covers it — the direct self-registration lets you choose the message type (SMS/MMS or RCS).
In Instasent, the CNMC process for RCS will switch on when the RCS channel launches (with the new version of the App): the channel will carry the compliance that corresponds to it, and the RCS agent will go through the CNMC just like an SMS sender. Until then, an RCS agent in Spain doesn't go through the CNMC — it's cleared once the operators approve it.
With RCS, the agent also has to be approved by the operators, and you need an enabled provider for RCS in Spain. You configure the RCS agent in RCS senders & verification.
Regulation
Alias registration comes from Spain's messaging regulation, designed to curb fraud (smishing) and impersonation:
- Orden TDF/558/2026 — sets the obligation and the date (15 September 2026).
- CNMC Circular 1/2026 — regulates the registry and the alias format (what can be registered, non-generic names).
- CNMC Circular 2/2026 — amends the previous one to allow acting through an authorised representative by means of an authorisation letter.
- CNMC electronic office — Sender Alias Registry management and the official registration guide.