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

# Outbound calling

Place outbound calls with one API request. Provide the agent, the number to call from, and one or more destination numbers in E.164 format, such as `+14155559876`.

`from_number_id` can be any phone number on your account. It does not need to be [assigned to an agent](/line/integrations/telephony/phone-numbers#assign-an-inbound-agent), and any agent can call from it.

<Tip title="Placing many calls at once?" icon="layer-group">
  This endpoint dials every number immediately, so destinations beyond your agent-call concurrency limit are rejected rather than queued. For larger lists, use [batch calling](/line/integrations/telephony/batch-calling), which queues up to 5,000 recipients and dials them as capacity frees up.
</Tip>

<Warning title="Compliance" icon="triangle-exclamation">
  You are responsible for complying with the regulations that apply to your calls, including the Telephone Consumer Protection Act (TCPA). See Cartesia's [Acceptable Use Policy](https://cartesia.ai/legal/acceptable-use.html).
</Warning>

<CodeGroup>
  ```bash cURL theme={null}
  curl -X POST "https://api.cartesia.ai/agents/calls" \
    -H "X-API-Key: $CARTESIA_API_KEY" \
    -H "Cartesia-Version: 2026-08-14" \
    -H "Content-Type: application/json" \
    -d '{
      "from_number_id": "ap_Q8PRh7lXyZsawXJmN2KcT5",
      "agent_id": "agent_Fo7pKNBUwLZxrTd6jvhpaE",
      "ringing_timeout_seconds": 30,
      "outbound_calls": [
        {
          "to_number": "+14155559876",
          "metadata": { "customer_id": "cust_123" }
        }
      ]
    }'
  ```

  ```python Python theme={null}
  import requests

  response = requests.post(
      "https://api.cartesia.ai/agents/calls",
      headers={
          "X-API-Key": "YOUR_CARTESIA_API_KEY",
          "Cartesia-Version": "2026-08-14",
          "Content-Type": "application/json",
      },
      json={
          "from_number_id": "ap_Q8PRh7lXyZsawXJmN2KcT5",
          "agent_id": "agent_Fo7pKNBUwLZxrTd6jvhpaE",
          "ringing_timeout_seconds": 30,
          "outbound_calls": [
              {"to_number": "+14155559876", "metadata": {"customer_id": "cust_123"}}
          ],
      },
  )
  response.raise_for_status()
  print(response.json()["calls"][0]["agent_call_id"])
  ```
</CodeGroup>

```json Response theme={null}
{
  "calls": [
    {
      "number": "+14155559876",
      "agent_call_id": "ac_3kF9mN2pQ8rT1vX6"
    }
  ]
}
```

The API returns `200` when the request is accepted. The `calls` array has one entry per destination, in the same order. Each entry carries either an `agent_call_id` or an `error`, so check every entry rather than the response status alone. Use `agent_call_id` with [Get Call](/api-reference/agents/calls/get-call) to follow the call.

`ringing_timeout_seconds` sets how long each destination rings before the attempt times out, from 5 to 80 seconds. The default is 60.

`metadata` accepts a JSON object that is stored on the call record.

<Note>Cartesia numbers place at most one outbound call per second. Faster requests are queued.</Note>