Vintage Car Phone Bluetooth Conversion

What? Why?

I have a vintage car phone in my 1993 Mitsubishi 3000GT VR4. It’s pretty cool, but it can’t make/receive calls because it relies on old 1G analog cellular service that has been extinct in the US since 2008. I wanted to make it functional so that I could actually use it for phone calls.

I could have taken the lazy approach and simply hacked a Bluetooth headset into the handset, wired up to the speaker and microphone. But I really wanted the full genuine experience of using the original car phone: the display, the button beeps, dialing a number and pressing “SEND” to place a call, etc.

I chose the most extreme and difficult approach: reverse engineer the car phone so that I could take complete control of the handset with custom electronics and microcontroller programming, replicate much of the original behavior from scratch, and integrate with a Bluetooth module so that calls can be routed through a modern cell phone.

Here’s a quick demo and disassembly video of my latest prototype:

Demo of my converted car phone, and disassembly to show the custom electronics.

And here’s a full tour of the complete car phone system in the car, and a more complete demonstration of many features of the Bluetooth conversion. Note: this is an older external plug-in adapter prototype.

Full tour and demo of the car phone system in my car.

Open Source Project

This is an open source project, free for anyone to use for personal non-profit purposes. All of the technical info, hardware designs, and microcontroller code are published on GitHub (still a work in progress). I have also documented my progress on this project from the beginning on the Electro-Tech-Online forum.

Highlights

Games

The original car phone did not have any games. In fact, this phone was released several years before Nokia first introduced the world to “Snake” on a phone. Every programmer’s dream is to develop games, and I’m no different. With full control of the car phone’s handset, now is my opportunity to become a mobile game developer!

The very restrictive 7×2 text display and high-latency display updates made it quite a challenge to implement any meaningful games, but that didn’t stop me from trying.

Snake

Snake game on my vintage car phone.

Memory

Memory game on my vintage car phone.

Tetris

Tetris game on my vintage car phone.

Replicating Original Behavior

Aside from extra features that I must add for managing the Bluetooth connection, and extra features I added for fun (e.g., games and extra ringtones), my goal was to create an authentic experience, matching the original behavior of the car phone as much as possible/reasonable. But how do you test the original behavior of a car phone that can’t make/receive calls any more? You buy an old Mobile Service Tester that can simulate service and calls for old 1G analog phones! Here’s a video demonstrating the Mobile Service Tester.

Demonstration of the Mobile Service Tester with the original car phone.

Media Coverage

My car phone project has been covered by a few media outlets. Here are several articles about my first plug-in external adapter prototype:

Follow This Project

If you are interested in future updates about this project, there’s a few options.

For very technical details about my progress, subscribe to this Electro-Tech-Online forum thread.

For less-technical details about my progress, join my Vintage Car Phones and Bag Phones Facebook Group.

For more visually-focused updates about this project, mixed in with other things I’m doing, follow me on Instagram and/or YouTube.