Whatever SMS gateway you use in Mexico, operators replace most A2P sender IDs with a short code. To show a brand name you need a pre-registered alphanumeric sender ID, available on Telcel, Movistar and AT&T. Marketing needs opt-in and a clear opt-out, and numbers on Profeco's REPEP list must not receive advertising.
Rules last checked: October 2026.
Regulator and market context
Telecoms in Mexico were regulated by the IFT (Instituto Federal de Telecomunicaciones) until a 2025 telecom law replaced it. Since October 2025 the regulator is the Comisión Reguladora de Telecomunicaciones (CRT), part of the Agencia de Transformación Digital y Telecomunicaciones (ATDT). As of 2026 the practical SMS rules (sender registration, overwriting, content filters) are set by the operators and passed on by route providers, so check them with your provider rather than expecting a single public regulation.
Sender ID registration
Alphanumeric registration is offered for Telcel, Movistar and AT&T. Providers differ on the wording: some call it optional, others say it is required if you want the sender ID preserved. In practice the result is the same: without registration your brand name will not reach the handset. Typical requirements:
- the requested sender ID and sample message content
- company name, address, website and tax or VAT number
- traffic type (OTP, notifications, marketing) and expected monthly volume
- a no-objection letter (NOC) or letter of authorization, especially for brand, financial or alcohol related sender IDs
Providers quote around three weeks to a month for approval as of 2026. Background in how sender ID registration works.
Sender ID types and replacement
| Sender type | What happens in Mexico |
|---|---|
| Registered alphanumeric | Preserved on the networks where it is registered |
| Unregistered alphanumeric | Overwritten with a short code or a random local number |
| Short code | Supported and preserved; dedicated codes take months to provision |
| Mexican long number | Not for marketing or one-way A2P; some providers allow OTP only, best effort |
| International long number | Delivered with the sender overwritten |
Traffic to smaller networks and MVNOs is usually delivered from a shared short code even when you hold a registration. Avoid well-known third-party brand names (for example messaging apps or social networks) as sender IDs unless you own them and have registered them. More in sender ID types and SMS short codes.
Content, opt-in and REPEP
Get opt-in before sending marketing and include clear opt-out instructions in every promotional message. Profeco runs the REPEP (Registro Público para Evitar Publicidad), where consumers register phone numbers to stop advertising calls and text messages; companies have 30 calendar days after registration to stop contacting a number. Financial institutions are covered by a separate Condusef register (REUS). Screen marketing lists against these registers and keep consent records.
Write the message body in Spanish when you use a domestic registered sender ID. Spanish letters such as á, í, ó and ú are not in the GSM-7 set, so a single one turns the message into Unicode with 70 characters per part; see GSM-7 vs Unicode encoding.
Restricted content and sending hours
Major providers list these categories as prohibited or blocked in Mexico:
- political messages and election campaigning (carriers block numbers that promote a candidate or cause)
- gambling, firearms, adult content, alcohol, cannabis and controlled substances
- money lending and loan offers, lead generation and text-to-pay
There is no single published curfew, but the common rule is not to send between 21:00 and 09:00 local time unless the message is urgent. Mexico has more than one time zone, so schedule by recipient region. See also SMS content restrictions.
Mobile networks and OTP traffic
The main networks are Telcel, AT&T Mexico and Movistar, with Altan Redes providing the shared wholesale network used by many MVNOs. Telcel carries the largest share of subscribers, so test it first.
For OTP, a registered alphanumeric sender or a dedicated short code gives the most predictable delivery. Long numbers are unreliable: sending many messages from the same number in a short window can trigger sender rotation. Keep the code at the start of the message, avoid links, and measure delivery time per network before sending volume. If you notice delivery reports that look too good to be true, read how to detect fake DLRs, and consider a voice or WhatsApp fallback for codes that do not arrive.
See coverage on the Mexico SMS destination page and our A2P SMS routes. VoIPMatcher sources the route from its carriers and manages it; buyers and sellers never see each other. Request a Mexico SMS route.
Frequently asked questions
Why does my SMS to Mexico arrive from a short code?
Mexican operators replace most A2P sender IDs with a short code. Only alphanumeric sender IDs pre-registered on Telcel, Movistar and AT&T keep the brand name, and traffic to smaller networks and MVNOs usually arrives from a shared short code even with a registration. Tell users which sender to expect, especially for OTP.
What is REPEP in Mexico?
REPEP (Registro Público para Evitar Publicidad) is the register run by Profeco where consumers list phone numbers to stop advertising calls and text messages. Companies have 30 calendar days after a registration to stop contacting that number. Financial institutions are covered by a separate Condusef register, REUS. Screen marketing lists against both.
How long does sender ID registration take in Mexico?
Providers quote around three weeks to a month as of 2026. You need the sender ID, sample content, company name, address, website and tax number, the traffic type and expected volume, and often a no-objection letter or letter of authorization, especially for brand, financial or alcohol related IDs.
Can I send OTP from a Mexican long number?
Some providers allow OTP from Mexican long numbers on a best effort basis, but it is unreliable: sending many messages from the same number in a short window can trigger sender rotation. A registered alphanumeric sender ID or a dedicated short code gives the most predictable OTP delivery in Mexico.
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