A vintage rotary phone has been given a completely new purpose thanks to a Raspberry Pi and Google Gemini. Instead of using the old telephone to call another person, picking up the receiver now connects the user to an AI assistant that can answer questions through a normal voice conversation (well, we suppose it depends on your definition of normal).

In any case, the project was created by Ramazan Eren Arslan using a Deutsche Bundespost FeTAp 791, an old German rotary telephone he found at a flea market. Rather than replacing its recognizable design with modern hardware on the outside, Arslan kept the classic appearance while modifying the internals to turn it into an AI-powered device.

How does it all work?

At the heart of the project is a Raspberry Pi 3 Model B, which was installed inside the phone after some of its original components were removed. A USB sound card was also added to handle audio, while the phone’s original handset is still used for speaking and listening. Even the older microphone and speaker were kept, giving conversations the kind of audio quality you’d expect from an old telephone.

The project has been designed to feel like making a traditional phone call. Picking up the handset plays a classic German dial tone, after which the rotary dial can be used to select a language. Dialing 1 connects to the German assistant, 2 selects English, and 3 selects Turkish. If nothing is dialed for four seconds, German is selected automatically.

After that, the phone establishes a session with Google Gemini 3.8 Live, allowing the user to speak to the AI and hear its responses through the handset. Gemini’s responses are streamed directly to the phone, so the conversation happens in real time rather than requiring users to type questions into a computer or smartphone.

The old controls remain useful as well. Turning the rotary dial affects the call setup just like an old telephone, while putting the handset back on the cradle immediately ends the AI session and stops the audio.

Despite being built around one specific German telephone, the idea isn’t necessarily limited to that model. Arslan says a similar setup should be possible with other vintage rotary phones, making the project an interesting example of how old hardware can be reused rather than simply displayed or thrown away.

About the Author

Abdul Haddi

Abdul is a tech writer and Editor for PC Guide, specializing in all things tech, gaming, and hardware.