> But then in the early 2000's when we switched to cell phones, filtering turned "not talking" into absolute dead silence, no background noise. As a matter of

> But then in the early 2000's when we switched to cell phones, filtering turned "not talking" into absolute dead silence, no background noise. As a matter of interest, the background noise generated on a digital squelched line is called comfort noise, and its addition is quite common for a number of reasons. https://en.m.wikipedia.org/wiki/Comfort_noise https://en.m.wikipedia.org/wiki/Comfort_noise