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

# Outbound call

> Trigger an outbound call to a specific number

## Basic

This API allows you to initiate outbound phone calls from a specified Millis AI voice agent to any given phone number.

#### Prerequisites

Obtain your API key from your [Millis AI Account](https://app.millis.ai/settings/keys).

#### API Details

* Method: POST

* URL:

```console theme={null}
https://api-west.millis.ai/start_outbound_call
```

* Headers:

```console theme={null}
Content-Type: application/json
Authorization: YOUR_API_KEY
```

* Body:

```json theme={null}
{
  "from_phone": "one of your agent's phone number",
  "to_phone": "receiver's phone number",
  "metadata": {
    key: value
  }, // Optional: any extra data to attach to the session
  include_metadata_in_prompt: true/false // Optional: option to include the metadata in the agent's system prompt
}
```

<Tip>
  Ensure the phone number includes the full international dialing format (e.g., +15555555555), with no dashes or spaces. (Only US phone nubers are supported)

  Retrieve your voice agent ID from the Agent Details page on the playground.

  <img src="https://mintcdn.com/millisai/E0S6YCSgju6oNy8Y/images/get-agent-id.png?fit=max&auto=format&n=E0S6YCSgju6oNy8Y&q=85&s=7b5c9d79b1533d80173e75df08f7755c" alt="title" width="776" height="502" data-path="images/get-agent-id.png" />
</Tip>

### Example Request using curl

```console theme={null}
curl -X POST https://api-west.millis.ai:8080/start_outbound_call \
-H "Content-Type: application/json" \
-H "Authorization: YOUR_API_KEY" \
-d '{"from_phone": "+1234567890", "to_phone": "+1987654321"}'
```