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

# Conversation window

> Understand how the WhatsApp 24-hour conversation window works

export const projectName = 'Hub Message';

## How does it work?

When a customer sends a message to your WhatsApp number, a **24-hour conversation window** opens. While this window is open, you can send any type of message: text, image, audio, video, document, etc.

If the customer sends another message, the 24-hour timer **resets**. This means as long as there's an active conversation, the window stays open.

## Inside the window (24h)

You can send **any message** freely using the [free messages](/en/messages/introduction) endpoints — no templates needed.

Messages sent within the window are classified as **Service** and are **free and unlimited**.

<Note>
  **Utility** templates sent within the 24h window are also **free**.
</Note>

## Outside the window (after 24h)

When the window closes, the only way to message the customer is through **Meta-approved templates** using the [Send template](/en/messages/send-template) endpoint.

| Category           | When to use                          | Cost                                |
| ------------------ | ------------------------------------ | ----------------------------------- |
| **Marketing**      | Promotions, campaigns, offers        | Charged per message sent            |
| **Utility**        | Confirmations, order updates, alerts | Free within window, charged outside |
| **Authentication** | OTP code, login verification         | Charged per message sent            |

<Warning>
  Without an approved template, you **cannot** send messages outside the 24h window. WhatsApp blocks the send.
</Warning>

## How to reopen the window?

There are two ways:

<Steps>
  <Step title="The customer sends a message">
    The simplest way. Any message from the customer opens a new 24h window immediately.
  </Step>

  <Step title="You send a template">
    Send an [approved template](/en/messages/send-template) (marketing, utility, or authentication). When the customer **replies**, the 24h window reopens and you can send [free messages](/en/messages/introduction) again.
  </Step>
</Steps>

## Free entry via ads

When the customer comes through **Click-to-WhatsApp** (Facebook ad) or a **Facebook Page CTA button**, the window extends to **72 hours** and all messages are **free** during that period, including marketing templates.

## Visual summary

| Situation                             | Can send free messages? | Template required? | Cost                |
| ------------------------------------- | ----------------------- | ------------------ | ------------------- |
| Customer sent a message (window open) | Yes                     | No                 | Free                |
| Window closed (over 24h)              | No                      | Yes                | Depends on category |
| Via Click-to-WhatsApp ad              | Yes                     | No                 | Free for 72h        |

## Next steps

<CardGroup cols={2}>
  <Card title="Free messages" icon="paper-plane" href="/en/messages/introduction">
    Send messages within the 24h window.
  </Card>

  <Card title="Send template" icon="file-lines" href="/en/messages/send-template">
    Send messages outside the window using templates.
  </Card>

  <Card title="Manage templates" icon="gear" href="/en/templates/introduction">
    Create and manage your approved templates.
  </Card>
</CardGroup>