line out telephone instrument
2007
this is a very subtle modification done to an ordinary telephone:
the phoneline jack has been replaced by a power supply jack. a new hole has been cut in the frame for a line out (female rca). the sound from the buttons and sound from the microphone on the reciever, can be picked up from this jack. the amount of dc input voltage is not that important. i've run as low as 6 volts and as high as 12 volts into it, although it does need around an amp of power. i think it's supposed to run on 8 volts, but it's not picky. you might notice that the plate around the buttons has been ripped off. i did not do this. i purchased it second hand in this condition. it does not effect anything but looks. if you're wondering (which you're not) what kind of phone this is, it's a "western electric 2500dm".
here's a sample of what it sounds like with some hum equalized out (i'll put a capacitor on it eventually to help reduce the hum): audio