Build a ChatGPT-Powered Phone Assistant with Twilio in Under 2 Hours

Brian Zalewski — Wed, 23 Apr 2025 06:56:44 +0000

Have you ever wanted to give ChatGPT a voice—literally? Thanks to Twilio’s open-source call-gpt project, you can deploy a fully functioning AI-powered phone assistant that talks with real callers using OpenAI and Deepgram... in under two hours.

I recently gave this project a spin, and it blew me away. So I put together a full walkthrough for developers who want full control over their own AI voice system. Whether you're building a smart receptionist, a voice bot for your app, or just exploring voice-first AI experiences, this setup is 💯.

👉 If you want the full guide (with diagrams, deeper insights, and a demo number you can call), check out the original article on my site:

📖 https://megabyte.space/build-a-chatgpt-powered-phone-assistant-with-twilios-call-gpt-in-under-2-hours/

What Is `call-gpt`?

Twilio Labs created call-gpt as an experimental but highly capable project that connects:

Twilio Programmable Voice (to handle calls)
OpenAI ChatGPT (to power the assistant)
Deepgram (for real-time speech-to-text)

This setup creates streaming, low-latency AI responses that feel conversational and natural over the phone. And yes—it even supports interruptions, memory between turns, and calling external tools or APIs based on user input.

And here's the kicker: everything is code-based and customizable. Unlike Twilio Studio (which uses a drag-and-drop interface), call-gpt puts you in full control.

Quick Features Overview

✅ Real-time conversations with ChatGPT

✅ Call interruption support (just talk over it!)

✅ Memory of chat context

✅ External tool/API calling

✅ Call recording and transcription (via Deepgram)

✅ Easy deploy via Fly.io

💡 Pro tip: Choose the Virginia region when deploying to Fly.io—it's the lowest latency region for OpenAI in this setup. Trust me, you'll feel the difference.

Real-World Use Cases

Here are just a few ways I could see devs using this:

🧑‍💼 Solo devs: Set up an AI receptionist to screen calls and take messages
🧑‍🔧 SaaS startups: Add a voice layer to your product or support
🏪 Small businesses: Offer 24/7 voice-based customer support
🧪 Hackers: Create voice-interactive apps for demos, art projects, or accessibility tools
🧠 Custom AI: Build a voice bot that pulls data from your own DB via caller ID matching

Code Peek: Customize the AI Prompt

All the magic happens in gpt-service.js. Here's a tiny example of what you can configure:


js
const prompt = [
  {
    role: "system",
    content: "You are a helpful and upbeat assistant for Megabyte Labs. Keep answers short and speak clearly."
  }
];
Want it to be formal, funny, or even wildly philosophical? Your bot, your rules.

Why This Beats Studio for Devs
Twilio Studio is great for quick no-code flows. But if you want to build with real AI logic, hook into APIs, or do anything beyond the basics—code wins.

call-gpt gives you:

Full control over GPT behavior

Easy environment variable setup via .env

Modular Node.js structure

Transparent, extensible architecture

Try It Out + Full Guide
I've put together a deep-dive blog post with the full step-by-step setup, how to deploy to Fly.io, tweak the prompt, and even connect a Twilio number.

👉 Check it out here:
🔗 https://megabyte.space/build-a-chatgpt-powered-phone-assistant-with-twilios-call-gpt-in-under-2-hours/

If you do end up using it, drop a comment—I’d love to see how you’re putting it to work. 🚀

Tags:
#twilio #chatgpt #openai #node #voiceai #flyio #webdev #twiliolabs #callgpt

DEV Community: Brian Zalewski

Build a ChatGPT-Powered Phone Assistant with Twilio in Under 2 Hours

What Is call-gpt?

Quick Features Overview

Real-World Use Cases

Code Peek: Customize the AI Prompt

What Is `call-gpt`?