> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dialtu.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Compliance and opt-outs

> STOP, HELP, START and A2P 10DLC registration

SMS is far more regulated than WhatsApp. Two things are mandatory: **honouring opt-outs** and
**registering your traffic** before you send.

## Keywords

Lumina recognises three keyword groups **before** the message reaches the model. They aren't
configurable.

| Keywords                                                  | What it does                          |
| --------------------------------------------------------- | ------------------------------------- |
| `stop`, `stopall`, `unsubscribe`, `cancel`, `end`, `quit` | Unsubscribes the contact and confirms |
| `help`, `info`                                            | Sends the help message                |
| `start`, `yes`, `unstop`                                  | Resubscribes the contact              |

<Warning>
  **The keywords are English only.** There's no Spanish list: a customer texting "BAJA" or
  "PARAR" does **not** trigger the automatic opt-out.

  In that case it depends on your prompt catching it. Add an explicit rule, for example: *"If
  the customer asks to stop receiving messages in any language, confirm it and perform the
  opt-out."*
</Warning>

### Matching is exact

The keyword has to be **the entire message**, not part of it. `"Please stop texting me"` does
**not** trigger it.

<Note>
  That's deliberate: if containing the word were enough, a message like *"stop by the shop at
  5"* would silently mute the customer, with no way for them to notice or undo it.

  Natural language is the AI's job — it can perform the opt-out when it detects the intent.
</Note>

### Opt-out is per contact

Not per conversation: once opted out, **that contact** stops receiving messages on this channel,
including future conversations. Releasing it is done manually from settings.

Opt-out confirmations are still sent even when the contact is already suppressed — that's what
regulation requires.

## A2P 10DLC registration

In the United States, all business-to-person traffic on local numbers must be registered. **It
isn't handled inside Dialtu**: it's a process with the carrier.

<Warning>
  **Start this before anything else.** Approval takes **days to weeks**. It's the critical path
  of any SMS project.
</Warning>

Things worth knowing before you submit:

<AccordionGroup>
  <Accordion title="The EIN must match tax records exactly">
    This is the most common rejection reason. The legal name and number must match what the tax
    authority holds, character for character — a trading name won't do.
  </Accordion>

  <Accordion title="Register the correct use case">
    Register it as **conversational / customer care**, not as marketing.

    <Warning>
      Misregistering the use case is grounds for **suspension**.
    </Warning>
  </Accordion>

  <Accordion title="Watch out for double opt-out confirmations">
    If you leave the carrier's automatic opt-out handling switched on, the customer receives
    **two confirmations**: the carrier's and Dialtu's.
  </Accordion>

  <Accordion title="A carrier-registered opt-out is final at the network level">
    Once the carrier records the opt-out, sends fail at the network level even if Dialtu still
    shows the contact as active. To receive messages again, the customer has to text **START to
    the carrier**, not just to you.
  </Accordion>
</AccordionGroup>

## Good practice

<Check>**Identify yourself in the first message.** Who you are and why you're writing.</Check>
<Check>**Mention how to opt out** in the first message of any conversation you start.</Check>
<Check>**Respect the hours.** Use time-based routing so you're not texting at 3am.</Check>
<Check>**Be brief.** Every segment is billed, and long messages get split.</Check>

## Back to the start

<Card title="Introduction to SMS agents" icon="comment-sms" href="/en/sms-agents/introduction">
  The full path through this section.
</Card>