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A2P SMS in Mexico: Rules, Operators and Sender Types

A2P SMS in Mexico explained: the CRT regulator, Telcel, AT&T and Movistar, sender types, consent and opt-out, Spanish encoding and OTP best practice.

Updated 9 min read

By OmniChannels.ai Editorial Team · Reviewed by BroadNet Messaging Solutions Team

SMS & OTP

Short answer

To send A2P SMS in Mexico, you route traffic to the networks of Telcel, AT&T Mexico and Movistar through a provider with direct operator connectivity, using an alphanumeric sender where the network supports it or a numeric long code or short code. The telecom regulator is now the Comisión Reguladora de Telecomunicaciones (CRT), which replaced the IFT. Marketing needs verifiable opt-in and a working opt-out, and sender requirements are confirmed per operator at onboarding.

On this page
  1. Who regulates A2P SMS in Mexico today?
  2. Which operators carry A2P SMS in Mexico?
  3. What sender types can you use in Mexico?
  4. What consent and opt-out rules apply to marketing SMS?
  5. How should you write Spanish SMS to avoid Unicode costs?
  6. How do you send OTPs and alerts in Mexico?
  7. A worked example: a Mexican online retailer
  8. What are the common mistakes and limits?
  9. How OmniChannels.ai helps

Key takeaways

  • Mexico's telecom regulator is the Comisión Reguladora de Telecomunicaciones (CRT); the IFT was replaced under the telecommunications law published in the Diario Oficial on 16 July 2025.
  • Our coverage data lists Telcel, AT&T Mexico and Movistar Mexico as the networks to plan for, with sender ID requirements set by the operators.
  • Marketing SMS needs verifiable consent that you can produce later, plus a one-step opt-out; consumers can also register with Profeco's REPEP to refuse advertising.
  • Spanish accents such as á, í, ó and ú are outside the basic GSM 7-bit alphabet, so a single accented letter can move a message to Unicode and shrink the segment.
  • Keep OTPs and alerts on a separate transactional route and sender from promotions so a marketing complaint never delays a login code.

This guide is for marketing, product and compliance teams that need to send application-to-person (A2P) SMS to Mexican mobile numbers: OTPs, order and appointment alerts, collections reminders and promotions. It explains who regulates the market, which networks you are really sending to, what sender types exist, what consent evidence to keep and how to avoid the encoding mistakes that make Spanish messages cost more. It is a practical overview, not legal advice.

Who regulates A2P SMS in Mexico today?

The telecom regulator is the Comisión Reguladora de Telecomunicaciones (CRT), a deconcentrated body of the Agencia de Transformación Digital y Telecomunicaciones. It replaced the Instituto Federal de Telecomunicaciones (IFT) under the Ley en Materia de Telecomunicaciones y Radiodifusión, published in the Diario Oficial de la Federación on 16 July 2025. The IFT website now carries a banner saying it is a historical archive and points to gob.mx/crt for current procedures.

That matters in practice because a large share of English-language SMS guides still say "IFT". If a vendor tells you to "register with the IFT", the information predates the change. Two other bodies touch your messaging:

  • Profeco (consumer protection) administers the REPEP, the public register where consumers ask not to receive advertising.
  • Data protection law: the new Ley Federal de Protección de Datos Personales en Posesión de los Particulares replaced the 2010 law in March 2025 and governs how you collect and use phone numbers.

As in most markets, you rarely deal with the regulator directly. Your licensed provider and the operators apply the rules to your traffic, so what you control is consent, content and sender choice.

Which operators carry A2P SMS in Mexico?

Plan for three networks. Our coverage data lists these routes for Mexico:

Operator Network code (MCC-MNC) Route in our data
Telcel 334-02 Direct
AT&T Mexico 334-30 Direct
Movistar Mexico 334-03 Direct

Because each network applies its own filtering, always test every campaign on all three networks before launch and compare delivery reports per operator, not just overall. If you want to see how our delivery statuses map to what happened on the network, read the message delivery status guide.

What sender types can you use in Mexico?

Mexico does not behave like the Gulf, where a registered alphanumeric ID is the norm. Our regulation data describes the options as an alphanumeric sender where the network supports it, or a numeric long code or short code. The requirements are set by the operators, and we confirm the current ones for each customer during onboarding.

Sender type What the customer sees Good for Watch out for
Alphanumeric A brand name OTPs and alerts where supported Support differs by network; one-way only
Long code A normal Mexican number Conversational flows, low volume Replies need handling; throughput is limited
Short code A short number High-volume campaigns, keyword opt-in Needs operator approval and longer setup

Do not assume the sender you used in another country will arrive unchanged. Our Mexico sender ID page summarises the current position, and the sender ID checker is a quick way to see what applies to your brand name. If you want our team to prepare and file the registration with you, see registrations; approval decisions stay with the operators.

Treat verifiable opt-in as mandatory for promotions. Our regulation data requires consent records retained in line with the local data-protection law, and a one-step opt-out (a STOP or SAIR keyword) that is honoured across the operator. Three rules of thumb keep you safe:

  1. Collect consent that names you. The person should know your brand will text them, what about, and how to stop.
  2. Keep the evidence. Store the source (web form, in-store tablet, WhatsApp), timestamp, wording and phone number for each consent.
  3. Respect refusals everywhere. Mexican consumer law bars sending advertising to people who said they do not want it or who are registered in the REPEP. Check your list against opt-outs before every send, and use the opt-in consent generator to draft capture wording.

We have not found a regulator-published time-of-day window for promotional SMS in Mexico. Schedule promotions for the recipient's local daytime, avoid late evenings and early mornings, and keep transactional traffic (OTPs, alerts) on its own route so it can run at any hour. Mexico spans several time zones, so schedule by the recipient's zone, not yours; the send time planner helps.

How should you write Spanish SMS to avoid Unicode costs?

Spanish is where many senders lose money without noticing. The basic GSM 7-bit alphabet used for standard SMS contains é, ñ, ü, ¿ and ¡, but not á, í, ó or ú. One of those letters in a message forces the whole message into Unicode (UCS-2).

Encoding Characters in a single message Characters per part when concatenated
GSM 7-bit 160 153
Unicode (UCS-2) 70 67

The numbers come from the 3GPP standard. A 150-character promotion with a single "ó" becomes a three-part message instead of one, which triples the number of segments you pay for. Your options:

  • Rewrite copy to avoid accented vowels where the meaning stays clear (not always appropriate for brand voice).
  • Accept Unicode and write shorter copy that fits 70 characters.
  • Move the long-form version to WhatsApp or RCS and keep SMS as a short pointer with a link.

Always run the final text through the SMS character counter. More detail on segments is in our guide to SMS character limits and Unicode.

How do you send OTPs and alerts in Mexico?

Keep OTPs, security alerts and order updates on a transactional route and sender, separate from promotions. Mixing them risks a complaint about a campaign delaying a login code. A sensible design:

  1. Send the code by WhatsApp authentication template when the user is reachable there; Meta supports Mexican Spanish with the template language code es_MX.
  2. Set a short timeout, then fall back to SMS if the WhatsApp message is not delivered.
  3. Rate-limit code requests per number and per IP to avoid artificial traffic; see SMS pumping fraud prevention.
  4. Keep the message short, name your brand, state the expiry and never include marketing text.

Our OTP and notifications solution supports this waterfall, and the OTP authentication guide goes deeper.

A worked example: a Mexican online retailer

"Casa Norte" (synthetic) sells home goods nationwide and wants OTPs at checkout, delivery alerts and a monthly promotion to 80,000 opted-in customers.

  • It splits traffic into two senders: a transactional one for OTPs and delivery alerts, and a separate one for promotions, and asks its provider which sender types each network accepts.
  • It rewrites its promotion template to fit 160 characters in GSM 7-bit, reserving a Unicode version for the segment that needs accents.
  • Before the first campaign, it sends a test to numbers on Telcel, AT&T and Movistar and compares delivery per network.
  • It adds a STOP instruction to every promotion and loads opt-outs into a suppression list shared by SMS and WhatsApp.
  • It schedules the promotion for late morning in each customer's local time, never overnight.

What are the common mistakes and limits?

  • Quoting the IFT. Procedures and contact points moved to the CRT.
  • Buying lists. Purchased numbers have no usable consent and invite complaints.
  • Ignoring per-operator results. An overall 95% delivery rate can hide a failing network.
  • Mixed traffic. Promotions on the OTP route put authentication at risk.
  • Treating lead times as promises. Our 5 to 10 business day range is a typical guide, not a commitment, and depends on operator review.
  • Unchecked Unicode. One accented vowel can multiply cost.

Rules and operator requirements change. Confirm the current position on the CRT site and with your provider before each new use case.

How OmniChannels.ai helps

OmniChannels.ai is powered by BroadNet, which connects directly to Telcel, AT&T Mexico and Movistar Mexico. We help with the sender and registration steps, offer SMS, WhatsApp and RCS from one platform with channel fallback, and give you per-operator delivery reports. See current rates on the Mexico SMS pricing page, then book a demo to plan your Mexico launch. For RCS, see RCS business messaging.

Frequently asked questions

Who regulates SMS in Mexico?

The Comisión Reguladora de Telecomunicaciones (CRT), a body of the Agencia de Transformación Digital y Telecomunicaciones, is the telecom regulator. It took over from the Instituto Federal de Telecomunicaciones (IFT) after the Ley en Materia de Telecomunicaciones y Radiodifusión was published on 16 July 2025. Many older guides still name the IFT, so check the date of any source you rely on.

Do I need to register a sender ID to send SMS in Mexico?

Requirements depend on the operator and the sender type. Our regulation data says sender ID requirements are set by the operators and are confirmed during onboarding, and that alphanumeric senders are supported where the network allows it, with numeric long codes and short codes as the alternative. Ask your provider which type each network accepts for your use case.

Can I send marketing SMS to Mexican customers without consent?

No, treat verifiable opt-in as mandatory. Mexican data-protection law requires a privacy notice and consent for the use of personal data, and consumers can ask not to receive advertising or register with Profeco's REPEP. Record the source, timestamp and wording of each consent, include an opt-out in every promotion and suppress anyone who opts out across all campaigns.

How long does it take to start sending SMS to Mexico?

Our published lead time for Mexico sender setup is 5 to 10 business days, which is a typical range and not a guarantee. Operator review, incomplete documents and the sender type you choose can all extend it. Submit your use cases, sample messages and company details early and keep launch dates flexible.

How many characters fit in one SMS in Spanish?

A single GSM 7-bit message holds 160 characters, but á, í, ó and ú are not in that alphabet, so one of them switches the whole message to Unicode (UCS-2), which holds 70 characters per single message and 67 per part when concatenated. Test your final copy in a character counter before you launch a campaign.

Should I use SMS or WhatsApp for OTPs in Mexico?

Use both through a fallback rather than choosing one. WhatsApp authentication templates suit users who have the app and a data connection, while SMS reaches any handset with mobile coverage. A common pattern is to send the code on WhatsApp first and fall back to SMS if it is not delivered within a short window.

Sources

  1. Comisión Reguladora de Telecomunicaciones (CRT)
  2. Ley en Materia de Telecomunicaciones y Radiodifusión (DOF, 16 July 2025)
  3. Ley Federal de Protección al Consumidor — Profeco
  4. Ley Federal de Protección de Datos Personales en Posesión de los Particulares (2025)
  5. 3GPP TS 23.040 — Technical realization of the Short Message Service
  6. Supported languages for message templates — Meta for Developers

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