This application demonstrates how to use Node.js, Twilio Voice and ConversationRelay, and the Open AI API to create a voice assistant that can engage in two-way conversations over a phone call. Other branches in this repository demonstrate how to add more advanced features such as streaming, interruption handling, and tool/function calling.

To use the app, you will need:

• Node.js 23.9.0: Download from here. Other versions may work, but I tested with this one.
• A Twilio Account: Sign up for a free trial here.
• A Twilio Number with Voice Capabilities: Instructions to purchase a number.
• An Open AI Account and API Key: Visit Open AI's platform here for more information.

You'll need to expose your local server to the internet for Twilio to access it. Use ngrok for tunneling:

ngrok http 8080

Copy the Forwarding URL and put it aside; it looks like https://[your-ngrok-subdomain].ngrok.app. You'll need it in a couple places.

Run the following command to install necessary packages:

npm install

Update Your Twilio Phone Number: In the Twilio Console under Phone Numbers, set the Webhook for A call comes in to your ngrok URL followed by /twiml.

Example: https://[your-ngrok-subdomain].ngrok.app/twiml.

Copy the example environment file to .env:

cp .env.example .env

Edit the .env file and input your Open AI API key in OPENAI_API_KEY. Add your ngrok URL in NGROK_URL (do not include the scheme, "http://" or "https://")

Start the development server:

node server.js

Call your Twilio phone number. After connection, you should be able to converse with the Open AI-powered AI Assistant, integrated over ConversationRelay with Twilio Voice!