Hello there
My work telephone uses a piezoelectric buzzer to create the ringtone for a call alert.
I suspect that the buzzer is being used to record room audio. I also suspect the recorded audio is then transmitted via RF. I'm not referring to a phone tap. Taps record telephone call conversations. This is a bug which records every sound that occurs in the room.
Ive disassembled many phones at our company and noticed that certain individuals have the polarity on the pizeobuzzer reversed. The phones that I suspect are compromised have the positive lead (red wire) connected to the positive terminal while the untampered phones have the negative lead (black wire) connected to the positive terminal.
By reversing the polarity is it possible to record room audio? Or would it allow for a carrier frequency to interact with the buzzer such that modulated RF would be emitted?
Here are some pictures of the telephone circuitry and buzzer:
http://bit.ly/1I0AYsd
http://bit.ly/1FdMcpB
http://bit.ly/1C1PoQh
Any help would be appreciated as I'm not an electronic/avr engineer.
My work telephone uses a piezoelectric buzzer to create the ringtone for a call alert.
I suspect that the buzzer is being used to record room audio. I also suspect the recorded audio is then transmitted via RF. I'm not referring to a phone tap. Taps record telephone call conversations. This is a bug which records every sound that occurs in the room.
Ive disassembled many phones at our company and noticed that certain individuals have the polarity on the pizeobuzzer reversed. The phones that I suspect are compromised have the positive lead (red wire) connected to the positive terminal while the untampered phones have the negative lead (black wire) connected to the positive terminal.
By reversing the polarity is it possible to record room audio? Or would it allow for a carrier frequency to interact with the buzzer such that modulated RF would be emitted?
Here are some pictures of the telephone circuitry and buzzer:
http://bit.ly/1I0AYsd
http://bit.ly/1FdMcpB
http://bit.ly/1C1PoQh
Any help would be appreciated as I'm not an electronic/avr engineer.
