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

# Create Chat Completion

> Implement text-based chat sessions with your UponAI chat agents via the API.

This guide explains how to implement chat functionality using the UponAI Chat API — start a session, generate responses, and end the session.

<Steps>
  <Step title="Create a Chat Agent">
    Before starting a chat session, you need a chat agent to handle the conversation.

    Refer to the [Website Widget guide](/Deploy/chat-widget) or the Create Chat Agent guide for setup instructions.
  </Step>

  <Step title="Create a Chat Session">
    Use the `create-chat` API endpoint to start a session. The API returns a `chat_id` you'll need for all subsequent requests.

    See the Create Chat API Reference for full parameter details.
  </Step>

  <Step title="Create a Chat Completion">
    Use the `create-chat-completion` endpoint to generate a response from your chat agent.

    The API returns the agent's response in the `messages` array. All conversation history is automatically stored — you don't need to manage conversation context yourself.

    See the Create Chat Completion API Reference for full parameter details.
  </Step>

  <Step title="Retrieve Chat Details">
    Retrieve details about a chat session using the `get-chat` endpoint, or list all sessions using `POST /v3/list-chats`.

    See the Get Chat API Reference and List Chats API Reference.
  </Step>

  <Step title="End the Chat Session">
    End a completed conversation using the `end-chat` endpoint.

    <Note>
      If **Auto-Close Inactive Chats** is enabled, chat sessions will automatically end when the timeout triggers. You can also end them at any time via the API.
    </Note>
  </Step>
</Steps>

## SMS Integration

UponAI also supports Twilio SMS integration, letting you deploy chat agents to receive and respond to text messages.

See the [Enable SMS guide](/Deploy/enable-sms) to set it up. Once configured, you'll have access to:

* **Make an outbound SMS** button to start a new SMS session
* Inbound and outbound SMS agent configuration
* Inbound webhook setup for receiving SMS messages

<Note>
  SMS conversations on a phone number can include multimedia (MMS). Text chat via the `create-chat-completion` API does **not** support images or other multimedia.
</Note>