In short: “Listen to telephone conversations on the radio!”
But before that here is a disclaimer:
All information provided in this post is for educational purposes only. I do not support nor encourage this monkey business. If you choose to make the device and hack your own phone; you, and only you will be responsible for the consequences. Happy building!
I thought of turning my old land line phone into a cool spy device. You know, like in the Bond movies, only this one’s a bit bulkier.
Internals… The FM transmitter is on the left with the phone circuit board on the right. The antenna is stuck with hot glue around the casing. I took 5V from somewhere in the back to power the transmitter and used 220 ohm resistor, was a bit difficult to solder. Be very careful not to short anything.
That’s all to it. Can be done to any land line phone, just take care of the power supply to the FM transmitter and the antenna. Drop in a line if you have any questions.
And I forgot to mention, land lines will soon be obsolete.