Some time in 1981, I think, a relative from the U.S. comes to visit us for the first time since he left the country many years before that. He was going to stay in our house for a couple of weeks. My parents told me that such visits were always "monitored" by KGB, and so I should be careful with expressing any kind of anti-soviet ideas (which I was known for in the school). In the end though, nobody was going to take this seriously: neither the possibility of KGB agents freezing in cold outside watching us through the windows, nor any kind of bugs installed in our house.
Something strange, however, had happened when our relative had finally arrived. Our phone went crazy. First of all, it was practically impossible to call or to take calls during that period. And besides, the phone's ringer started giving a single "ding" twice a day, exactly at 9 in the morning and 9 in the evening.The KGB, it seems, was using the ringers of telephones as crude microphones, responding to sound vibrations and feeding a very weak signal back into the phone line; when a house was noted as being of sufficient interest, a powerful amplifier could make the signal just about intelligible. The KGB only got caught out (to the extent of allowing a young boy to figure out what was happening, at least) due to the dilapidated condition of the Soviet phone system, and the tendency for lines to get crossed from time to time.
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