Or maybe are sensitive to the tiny change in electric fields from the phone wires.
But that would be only milliseconds before the speakers actually move and produce sound.
It’s very anecdotal.
What I mean is that “the hits” stand out in our minds as proof of something, but we quickly forget the hundreds or thousands of “misses”
Setting up a phone call is not instantaneous. It can take upto a few seconds, and there’s a lot of communication going on between the handset and the cell-tower in that time.