Quickstart

Get your first AI voice agent up and running in just a few minutes. This quickstart will walk you through making an automated phone call using Ultravox and Twilio.

Don’t use Twilio?Ultravox Realtime enables you connect your voice AI agents via telephony providers, Websockets, SIP trunks, or in web/native apps.

Prerequisites

Before you begin, make sure you have:

Ultravox account

API key

Create one in the Ultravox console

Twilio account

with Account SID, Auth Token, and a phone number

Node.js 20

or higher installed

Make Your First Outbound Call

Here’s the core concept in 3 steps:

1. Create an Ultravox Call

const response = await fetch('https://api.ultravox.ai/api/calls', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-API-Key': 'YOUR_ULTRAVOX_API_KEY'
  },
  body: JSON.stringify({
    systemPrompt: "You are Steve, a friendly AI assistant calling to check in.",
    medium: { "twilio": {} },
    firstSpeakerSettings: { user: {} }
  })
});

const { joinUrl } = await response.json();

2. Make the Phone Call

const call = await twilioClient.calls.create({
  twiml: `<Response><Connect><Stream url="${joinUrl}"/></Connect></Response>`,
  to: '+1234567890',
  from: 'YOUR_TWILIO_NUMBER'
});

3. Your AI Agent Talks!

When the recipient answers, your AI agent starts the conversation.

Want the complete working example? Check out our detailed outbound call example with full setup instructions, error handling, and more.

How It Works

This quickstart example:

Creates an Ultravox call configured for outbound phone calls
Uses Twilio to initiate the phone call to your target number
Connects the call to your AI agent using Ultravox’s streaming API
Starts the conversation when the recipient answers

The AI agent follows the system prompt you provide and can have natural voice conversations with the person who answers.

More Examples

Ready to explore more? Our examples repository includes complete implementations for:

Incoming Phone Calls - Handle inbound calls with AI agents
Outbound Phone Calls - Handle outbound calls with AI agents

Explore All Examples →

What’s Next?

For Phone Integration:

Learn about Telephony Providers or SIP.
Check out the Inbound Calls Example
Implement Call Transfers to human agents

For Web and Native Integrations:

Try our WebRTC SDK for WebRTC-based voice chat
Build custom voice interfaces for your applications

Advanced Features:

Create Custom Voices that match your brand
Add Custom Tools to give your agents special capabilities
Set up Webhooks for real-time call notifications

Need Help?

Discord: Join our community for real-time support
Documentation: Browse our complete API reference
Examples: More working code in our GitHub repository

Start building powerful voice AI applications with Ultravox today!

Getting Started

Agents & Calls

Telephony

Web, Apps, Websockets

Tools

Voices

Webhooks

Noise & VAD

Prerequisites

Make Your First Outbound Call

1. Create an Ultravox Call

2. Make the Phone Call

3. Your AI Agent Talks!

How It Works

More Examples

What’s Next?

For Phone Integration:

For Web and Native Integrations:

Advanced Features:

Need Help?

​Prerequisites

​Make Your First Outbound Call

​1. Create an Ultravox Call

​2. Make the Phone Call

​3. Your AI Agent Talks!

​How It Works

​More Examples

​What’s Next?

​For Phone Integration:

​For Web and Native Integrations:

​Advanced Features:

​Need Help?

Prerequisites

Make Your First Outbound Call

1. Create an Ultravox Call

2. Make the Phone Call

3. Your AI Agent Talks!

How It Works

More Examples

What’s Next?

For Phone Integration:

For Web and Native Integrations:

Advanced Features:

Need Help?