# POST /v1/sessions/{session_id}/voice

> Called from the user's browser with the session's token and its WebRTC offer; answers the model's answer.

In [Sessions API](https://vestra.ai/developers/reference/api/sessions.md): Bash in a browser: its live screen, a voice call, or the whole of Bash inside your app.

Send `Authorization: Bearer vk_test_...` on every call.

Called from the user's browser with the session's token and its WebRTC offer; answers the model's answer. Audio then flows straight to the voice model, and everything said lands in the session's conversation. For a session opened with voice.

A session's token. On the card: [`talk`](https://vestra.ai/developers/talk.md). Every call here is a checked sample.

## Request

Path:

- `session_id` (`string`, required): The session's id (`ses_...`).

Body:

- `sdp` (`string`, required): The browser's WebRTC offer (its SDP), in at most 65,536 characters. Limits: 1 to 65536 characters.

## Answers 201

- `object` (`"session_voice"`): Always session_voice.
- `sdp` (`string`): The answer to the browser's offer (its SDP): hand it to the browser's connection.
- `voice` (`string`): The voice Bash speaks in.

## Code

**HTTP**

```bash
# Call in an existing conversation. Open the session's url, and the page joins the call.
curl "$VESTRA_BASE_URL/v1/sessions" \
  -H "Authorization: Bearer $VESTRA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "user_id": "traveller-42", "conversation_id": "conv_8f2k", "voice": true }'

# Connect your own voice client. The session's page does this for you: it sends the browser's WebRTC offer
# with the session's own token, and gets the answer back. Call it yourself only if you build your own client.
curl "$VESTRA_BASE_URL/v1/sessions/ses_8h2/voice" \
  -H "Authorization: Bearer $SESSION_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "sdp": "the WebRTC offer from the browser" }'
```

**MCP**

```json
{
  "method": "tools/call",
  "params": {
    "name": "talk",
    "arguments": { "user": "traveller-42", "conversation": "conv_8f2k" }
  }
}
```

**TypeScript, Python, CLI**: No sample in your language for this route, so here it is over HTTP.