# Voice Agent Message Flow

This guide walks you through implementing the correct message flow when building a Voice Agent client. Follow these steps to establish a connection, configure settings, and handle the conversation loop.

## Establish the Connection and Receive Welcome

1. Open a WebSocket connection to the Voice Agent endpoint.

2. Wait for the server to send a `Welcome` message confirming the connection:

```json
{ "type": "Welcome", "request_id": "uuid" }
```

:::callout{intent="warning"}
Do not send any messages until you receive the `Welcome` message.
:::

## Configure Settings and Wait for Confirmation

3. Send a `Settings` message with your audio and agent configuration:

```json
{
  "type": "Settings",
  "audio": {
    "input": {
      "encoding": "linear16",
      "sample_rate": 16000
    },
    "output": {
      "encoding": "linear16",
      "sample_rate": 24000,
      "container": "none"
    }
  },
  "agent": {
    "listen": { "provider": { "type": "deepgram", "model": "nova-3" } },
    "think": {
      "provider": { "type": "open_ai", "model": "gpt-4o-mini" }
    },
    "speak": { "provider": { "type": "deepgram", "version": "v2", "model": "flux-kit-en" } }
  }
}
```

4. Wait for the server to send a `SettingsApplied` message:

```json
{ "type": "SettingsApplied" }
```

:::callout{intent="warning"}
Do not send audio or inject messages until you receive `SettingsApplied`.
:::

## Stream Audio and Inject Text

5. After receiving `SettingsApplied`, begin streaming binary audio data (PCM) continuously to the server.

6. Optionally, send text input using [`InjectUserMessage`](/guides/self-hosted-deployments-3-voice-agent-inject-user-message):

```json
{ "type": "InjectUserMessage", "content": "Hello" }
```

## Handle Server Events

7. Process the following events as the conversation progresses:

| Event                                                                                                                                                               | Description                                                                 |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------- |
| [`UserStartedSpeaking`](/guides/self-hosted-deployments-3-voice-agent-user-started-speaking)                                                                        | User began talking. Stop any audio playback immediately to handle barge-in. |
| [`ConversationText`](/guides/self-hosted-deployments-3-voice-agent-conversation-text)                                                                               | User's speech has been transcribed.                                         |
| [`AgentThinking`](/guides/self-hosted-deployments-3-voice-agent-agent-thinking)                                                                                     | Agent is processing the user's input.                                       |
| [`ConversationText`](/guides/self-hosted-deployments-3-voice-agent-conversation-text)                                                                               | Agent's text response is available.                                         |
| `[binary audio]`                                                                                                                                                    | Agent's audio response. Play this through your audio output.                |
| [`AgentAudioDone`](/guides/self-hosted-deployments-3-voice-agent-agent-audio-done)                                                                                  | Agent finished speaking.                                                    |
| [`Error`](/guides/self-hosted-deployments-3-voice-agent-errors-warnings#error) / [`Warning`](/guides/self-hosted-deployments-3-voice-agent-errors-warnings#warning) | Issues occurred during processing.                                          |

## Message Flow Diagram

```mermaid
sequenceDiagram
    participant CLIENT
    participant SERVER (Deepgram)

    CLIENT->>SERVER (Deepgram): Connect
    SERVER (Deepgram)-->>CLIENT: Welcome
    CLIENT->>SERVER (Deepgram): Settings
    SERVER (Deepgram)-->>CLIENT: SettingsApplied

    loop Conversation Loop
        CLIENT->>SERVER (Deepgram): Binary Audio
        Note over CLIENT,SERVER (Deepgram): (or InjectUserMessage)
        SERVER (Deepgram)-->>CLIENT: UserStartedSpeaking
        SERVER (Deepgram)-->>CLIENT: ConversationText
        SERVER (Deepgram)-->>CLIENT: AgentThinking
        SERVER (Deepgram)-->>CLIENT: ConversationText
        SERVER (Deepgram)-->>CLIENT: [binary audio]
        SERVER (Deepgram)-->>CLIENT: AgentAudioDone
    end

    CLIENT->>SERVER (Deepgram): Close
```

## Verify the Implementation

Confirm your implementation works correctly by checking:

- You receive a `Welcome` message immediately after connecting.
- You receive a `SettingsApplied` message after sending your `Settings`.
- The agent responds with `ConversationText` and binary audio when you speak or inject text.
- Audio playback stops when you receive `UserStartedSpeaking` (barge-in detection).

## Next Steps

- [Configure the Voice Agent](/guides/self-hosted-deployments-3-configure-voice-agent) for detailed settings options.
- [Outputs: Server Events](/guides/self-hosted-deployments-3-voice-agent-outputs) for detailed event documentation.

## Related pages

- [Voice Agent TTS Controls](./self-hosted-deployments-3-voice-agent-tts-controls.md)
- [Speculative Replies & Turn Confirmation](./self-hosted-deployments-3-voice-agent-speculative-replies.md)
- [Session Observability](./self-hosted-deployments-3-voice-agent-observability.md)
- [Voice Agent Audio & Playback](./self-hosted-deployments-3-voice-agent-audio-playback.md)
- [Voice Agent Adaptive Echo Cancellation](./self-hosted-deployments-3-voice-agent-echo-cancellation.md)

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