If you’re into DIY tech projects, a Raspberry Pi is one of the best pieces of equipment you can get. These small computers may not look like much, but they pack impressive power in a compact size. We’ve seen plenty of creative Raspberry Pi projects that use AI technology, including DeepSeek running on a Raspberry Pi 4. But if that wasn't enough, we just came across a unique DIY project that transforms a vintage telephone into a ‘ChatGPT hotline.’

This retro-style ChatGPT hotline lets you have real conversations where the AI remembers what you’ve said previously. All you have to do is dial a number and start talking. But the best part? This project’s design “blends nostalgic hardware with cutting-edge AI to create a unique and tactile way to interact with large language models.”

Meet Retro Calling

This vintage ChatGPT hotline DIY project runs on a Raspberry Pi 4 and requires some technical know-how to set up. At its core, a Python script controls the phone's functionality, monitoring when you pick up or hang up the receiver using a hook switch and detecting numbers dialed on the rotary dial.

When you lift the receiver, it plays a dial tone, just like a classic landline. If you dial 1, the system activates speech recognition using OpenAI’s Whisper API, allowing it to listen and convert your spoken words into text. ChatGPT then processes your input and generates a response, which is transformed into speech using OpenAI’s text-to-speech (TTS) API. The reply is played through the phone's original speaker, letting you have a real-time conversation with ChatGPT through a vintage handset.

How to use Retro Calling

Using Retro Calling is simple as it works just like an old-school landline. All you have to do is dial the right number, which in this case is 1, and start talking as you normally would. The magic happens in the background, seamlessly processing your voice and responding in real-time. Here's a quick step-by-step guide to get you started with Retro Calling:

• Pick up the phone receiver – you’ll hear a dial tone
• Dial “1” to connect to ChatGPT
• Speak naturally – your speech is transcribed and sent to ChatGPT
• Listen to ChatGPT’s response through the handset
• Continue the conversation – ChatGPT remembers previous exchanges
• Hang up to end the conversation

Source: Hackster

That said, if you’re interested in making your own Retro Calling project, you can check out the official Hackster page. It includes everything you need, from schematics and code to software setup, helping you build one from scratch. And if you own the latest Raspberry Pi 5 and want to create something even more powerful, you can check out our Raspberry Pi 5 best uses guide to kickstart your DIY journey.

About the Author

Hassam Nasir

Hassam boasts over seven years of professional experience as a dedicated PC hardware reviewer and writer.