As a kid, i used to use my ancient portable phone to walk down the street and tune into other phones, and baby monitors. I remember one mother always singing itailian sounding songs to quiet her child and found it touching. Then I realized I was basically peering in to the private lives of those around me to a weird level. Things later went digital, more consumer spectrum opened up, and these 'hacks' largely stopped working. I had moved on to computers by that time.