A trip down phone-phreak memory lane

The ProjectMF Blue Box

Arduino Blue Box

Old Blue Box Hardware Page

Remind Me Again What a Blue Box Is?

A blue box generates the tones that controlled the old long-distance telephone network. Typically blue boxes are handheld electronic devices with buttons or a dialpad like a Touch-Tone phone, but they can also be implemented in software on a computer. Blue boxes typically have an external speaker that emits the tones, and it gets held up to the moutpiece of a telephone to make a call with the blue box. See the Wikipedia article for more details.

If you're going to play with Project MF, you'll need a blue box.

Ok, So How Do I Get One?

One option is to download a software blue box for Windows. (You will also have to install Microsoft's.net framework.) This program will let you generate blue box tones through your PC's sound card and speakers.

But we think a far cooler option is to build your own. It's a pretty simple project, especially if you know anything about electronics. We already have a design for a simple yet capable blue box called the Project MF Blue Box.

This is an Arduino-based "Blue Box". It produces the "traditional" Blue Box 2600Hz tone and MF (multi-frequency) tones, but does much more! It also produces 12 tone signalling systems used by phone phreaks to hack other more exotic system in the US and overseas, including early pre-cellular mobile telephone systems from the 50s, 60s, and 70s.

The box has 12 non-volatile tone sequence storage memories that can store and play back up to 32 tones each. Each memory saves the tone mode as well. All operating parameters, such as tone duration, volume level, backlight status, reminder beep status, and current tone mode are saved to non-volatile EEPROM memory automatically and are restored when the box is powered up. EEPROM errors are automatically detected and corrected when the box is powered on.

An optional LCD provides full information of the operating status of the box and enhances the appearance and user-friendliness of the unit.

This box features sine-wave tone generation using PWM wave-table lookup techniques. It sounds much better than generating the tones using the two-pin square wave output techniques utilized by the standard Arduino "Tone" library.

I designed this new blue box, as I was out of the PCB boards for my older PIC-based blue box design and was looking for a way for others to easily construct a blue box for use with the ProjectMF system, using inexpensive and commonly available parts. This design is easily the most full-featured and technically sophisticated blue box design available. I am a telecommunications and software engineer and took great pains to be sure all of the tone modes are accurately represented. The code has been thoroughly debugged and well-tested.

The following modes are supported. Note that ALL of these modes are obsolete (well, not DTMF!) and no longer work on "real" public telephone systems, except for private systems (like ProjectMF) set up for historical purposes. They are included to preserve the sounds of these old tone signalling systems:

Questions? Email bluebox@projectmf.org.