Sender IDs in Mexico and Brazil explained
How sender identity works in Mexico and Brazil: alphanumeric senders, short codes and long numbers, and the registration each path needs.
This page is not legal advice.
A sender ID is the identity a recipient sees on a message. In Mexico and Brazil it takes three forms: an alphanumeric brand string, a short code or a long number. Each form has its own registration and reply behavior, and a sender registered in one market does not carry into another.
Key facts
- A sender ID is a per-country registration, not a display name.
- An alphanumeric sender is a brand string of up to 11 characters and usually cannot receive replies.
- Mexico links every mobile line to an identified holder; a business sender still needs its own registration.
- Brazil allocates access codes under Anatel's General Numbering Regulation; sender registration stays per program and operator.
On this page
A registration, not a label
The string a recipient sees is the last step of a registration process, not a field you type at send time. The market, the sender type and the route decide which string can appear. Change the market and the same brand may need a new application, a local entity or a different sender type. Change the sender type and the reply path, the lead time and the content filters change with it.
That is why a sender ID is better planned as a per-market asset than as a global setting. A brand that runs one program in Mexico and another in Brazil has two registration files, two approval records and possibly two sender strings. The SMS rules tool lists the rules we hold for each market; the registration itself is confirmed per sender.
Three sender types
| Three sender types | Alpha sender | Short code | Long number |
|---|---|---|---|
| Reply path | Usually no | Yes | Yes |
| Registration | Per market | National allocation | Per market |
| Best for | One-way alerts | High-volume two-way | Two-way with a local number |
Text description
An alphanumeric sender shows a brand string, is usually limited to 11 characters and usually cannot receive replies. A short code is a numeric sender allocated for high-volume two-way programs. A long number is a full telephone number that can carry two-way traffic and looks like a normal phone number.
The three paths
An alphanumeric sender carries a brand name instead of a number. It is recognizable and fits one-way notifications, but most networks do not route replies back to it. The 3GPP address format allows up to 11 characters, and a network may rewrite the string if it does not match the registered value.
A short code is a numeric sender allocated for a program. It supports two-way traffic and is familiar to consumers, but the allocation is tied to the program and can take time. A long number is a full telephone number in the national plan. It supports two-way traffic, looks ordinary and fits conversational or fallback use, but it is exposed to portability, recycling and number changes.
The registration sequence
Sender registration
- 1 Collect the legal entity and use case
- 2 Register the sender
- 3 Approval Current step
- 4 Send and monitor
Text description
The applicant collects the legal entity, the use case and the sample content. The sender is submitted to the operator or the aggregator that will carry the traffic. The application is reviewed and approved, sometimes with conditions. Only then does traffic start, with monitoring for rejections and content blocks.
Choose a sender type in five questions
-
Must the recipient reply?
If yes, choose a short code or a long number. An alphanumeric sender is one-way in most networks.
-
Is the volume steady or campaign-based?
A high-volume two-way program fits a short code. A low-volume notification flow may fit a long number or an alphanumeric sender.
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Which market, and does it require a local entity?
Confirm the documents and the authorized representative before you choose the string.
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How much lead time can the launch absorb?
Lead time is confirmed per sender. Do not put a date in the plan until the provider confirms it for your application.
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What is the fallback if the sender is rejected?
Name a second sender type and a second route before launch, so a rejection does not stop the program.
Mexico
Mexico's telecom regulator, the Comisión Reguladora de Telecomunicaciones (CRT, formerly IFT), requires every mobile line to be linked to an identified holder before service is enabled. The 2025 line-identification guidelines set that rule and the documents behind it. The rule covers the subscriber line; it does not register a business sender on its own.
A business sender is registered through the operator or the aggregator that carries the traffic. The documents, the entity that must hold the registration and the lead time are confirmed per sender. Long numbers follow the line rules. An alphanumeric sender is a separate application. Content rules interact with sender rules: a registered sender can still be filtered if the template trips a category or a link rule.
Brazil
Anatel allocates access codes under the General Numbering Regulation (Resolution 709/2019). A short code follows that allocation path and is tied to a service and a program. Alphanumeric and long-number senders follow operator registration, which is separate from the access-code allocation.
For promotional content, Anatel's consumer regulation (Resolution 765/2023) requires the consumer's prior, free and express consent and a way to cancel at any time. That consent rule sits alongside the sender registration; one does not replace the other. Keep the opt-in record and the opt-out path with the sender file.
What to check, and the usual mistakes
Ask who submits the application, who receives the approval and who owns the renewal. Ask what evidence the provider will give you: an approval reference, the registered string and the route that carries it. Ask what the fallback sender is and what happens if the application is rejected. Ask whether the sender survives a route change.
The usual mistakes are assuming one sender covers both countries, expecting replies to an alphanumeric sender, launching without a recorded opt-in and leaving registration to the last week. Another is treating approval as a delivery fix: registration grants the identity, but the route and the content still decide whether the message arrives.
Check what you learned
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A campaign needs replies from customers in both Mexico and Brazil. Which sender type do you shortlist?
A short code or a long number. An alphanumeric sender usually cannot receive replies, and each market registers its own sender.
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A provider says the sender is approved. What else do you need before launch?
The registered string, the route that carries it, the reply path if you need one, and a fallback if the route or sender fails.
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Why does a Mexican line-identification rule not approve a business sender?
It links the subscriber line to a person. The business sender is a separate registration held by the operator or aggregator.
Answers are revealed on request. Nothing is scored, stored or sent.
FAQ
Can one sender cover both countries?
How long does registration take?
Can recipients reply to an alphanumeric sender?
Do we need opt-in for transactional messages?
What happens if a sender is rejected?
Terms you'll meet
Related
- Connecting over SMPP and HTTP
Take a test route to production without breaking binds, windows or receipts: bind, throughput, keep-alive, encoding, callbacks and failure handling.
- Global A2P sender-ID playbook
How sender IDs work across markets: alphanumeric, numeric and short-code paths, registration expectations and country examples.
- A2P SMS
Application-to-person SMS is traffic an application sends to a handset, such as a verification code or a transaction alert, via a registered sender.
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