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

# Inbound Phone Calls

> Connect inbound phone calls to an AI agent in 6 minutes.

<Note>
  This is the full example of the [Inbound Call Quickstart](/gettingstarted/quickstart/telephony-inbound).
</Note>

This guide walks you through connecting inbound phone calls using Twilio to an Ultravox agent.

## Prerequisites

* Node.js 20 or higher
* A Twilio account with:
  * Account SID
  * Auth Token
  * Phone Number
* An Ultravox API key
* For incoming calls: A publicly accessible URL for your webhook (e.g., using ngrok)

## Set-up and Installation

<Steps>
  <Step title="Get the Source Code">
    Copy all the code locally from the [`twilio-inbound-quickstart-js`](https://github.com/fixie-ai/ultravox-examples/tree/main/telephony/twilio-inbound-quickstart-js) example.
  </Step>

  <Step title="Install the Required Dependencies">
    ```bash theme={null}
    pnpm install
    ```

    or

    ```bash theme={null}
    npm install
    ```
  </Step>
</Steps>

### Configure Twilio Webhook

<Steps>
  <Step title="Make Your Server Publicly Accessible">
    Use ngrok or a similar service to create a public URL for your local server:

    ```bash theme={null}
    ngrok http 3000
    ```
  </Step>

  <Step title="Set Up Webhook">
    1. Go to your Twilio Console
    2. Navigate to your phone number's configuration
    3. Under "Voice & Fax", set the webhook URL for incoming calls to:
       `https://your-ngrok-url/incoming`
  </Step>
</Steps>

### Update Configuration

The AI assistant will introduce itself as Steve and have a conversation with the recipient. You need to update the variable for the Ultravox API key. You may also (optionally) update the system prompt.

* `ULTRAVOX_API_KEY`: Your Ultravox API key
* `SYSTEM_PROMPT`: Instructions for the AI agent's behavior

```js Configuring Variables theme={null}
// Ultravox configuration
const ULTRAVOX_API_KEY = 'your_ultravox_api_key_here';
const SYSTEM_PROMPT = 'Your name is Steve. You are receiving a phone call. Ask them their name and see how they are doing.';
```

### Start the Server

Run the server:

```bash theme={null}
pnpm start
```

or

```bash theme={null}
npm start
```

Now, when someone calls your Twilio number, they'll be connected to your AI assistant.

## Next Steps

1. Check out the [Outbound Phone Call](/gettingstarted/examples/outbound-phone-call) example.
2. Ultravox Realtime provides telephony integrations for Telnyx, Twilio, Plivo, and Exotel. Learn more [here](/telephony/overview).

### Additional Resources

* [Twilio Documentation](https://www.twilio.com/docs)
* [Express.js Documentation](https://expressjs.com/)
* [ngrok Documentation](https://expressjs.com/)