> ## 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.

# Cartesia numbers

> Provision and manage Cartesia phone numbers for your agents.

Cartesia provides US phone numbers at no charge for the number itself. The number of slots depends on your subscription plan:

| Plan       | Phone number slots |
| ---------- | ------------------ |
| Free       | 1                  |
| Pro        | 3                  |
| Startup    | 5                  |
| Scale      | 10                 |
| Enterprise | Custom             |

Slot limits apply only to Cartesia-provisioned numbers. Numbers imported from [Twilio](/line/integrations/telephony/twilio/integration) or connected through a [SIP trunk](/line/integrations/telephony/sip-trunking) do not use slots and are billed by your own provider.

Cartesia-provisioned numbers have two limits:

* **US numbers only.** Every Cartesia number is a US number.
* **Outbound to US only.** Outbound calls can only reach US destinations, regardless of your agent's region.

## Provision a number

<Tabs>
  <Tab title="Playground">
    1. Go to **Phone Numbers** in the sidebar.
    2. Click **Add Number**, then **Cartesia Number**.
    3. Enter a name for the number.
    4. Optionally assign an agent.

    <Frame caption="Cartesia provisioning panel">
      <img src="https://mintcdn.com/cartesia-2650f86a/cyPOLB5BGhebR1Zv/assets/images/agents/telephony/provision-panel.png?fit=max&auto=format&n=cyPOLB5BGhebR1Zv&q=85&s=88b7c49fbabb0c976f48ef1bae339cee" alt="Provisioning a Cartesia number" width="2886" height="1920" data-path="assets/images/agents/telephony/provision-panel.png" />
    </Frame>
  </Tab>

  <Tab title="API">
    ```bash theme={null}
    curl -X POST "https://api.cartesia.ai/agents/phone-numbers/provision" \
      -H "X-API-Key: $CARTESIA_API_KEY" \
      -H "Cartesia-Version: 2026-08-14" \
      -H "Content-Type: application/json" \
      -d '{ "label": "My Agent Number" }'
    ```
  </Tab>
</Tabs>

<Note>
  If you have used every slot, delete an existing Cartesia number or upgrade your plan to add more.
</Note>

## Delete a number

Deletion is permanent. The number is released and cannot be recovered. Unassign the number from its agent first.

<Tabs>
  <Tab title="Playground">
    1. Go to **Phone Numbers** and open the number.
    2. Unassign the number from its agent.
    3. Click **Delete**.
  </Tab>

  <Tab title="API">
    ```bash theme={null}
    curl -X DELETE "https://api.cartesia.ai/agents/phone-numbers/YOUR_PHONE_NUMBER_ID" \
      -H "X-API-Key: $CARTESIA_API_KEY" \
      -H "Cartesia-Version: 2026-08-14"
    ```
  </Tab>
</Tabs>