Wait for people to learn about that you can listen in virtually anywhere through fiber-optic cables, as sound waves are enough to redirect the light in the cable to a measurable degree by "bending" the cable itself. Special devices to filter these variances out and transform them back to audio signals are a thing. It's only per line though, as any repeating device will just output a new cleaned up signal again.

Oh well, there have always been ways to snoop on someone like that. Back in the day it was CRTs emitting measurable waves through the neighborhood, with some papers even going as far as restoring the displayed image through a wall. Nowadays it's fiber and WiFi, and those seem to be much easier to work with even. Plus everyone carries a device that is tracked by their mobile provider's cell network. shrug

You can also listen for audio simply by measuring any vibrating surface with a laser. Which goes all the way back to the late 40s, used by the USSR. |

Fun fact, it was invented by Leon Theremin. The inventor of the Theremin.

Fiber optic interrogators are (for now) expensive and bulky, so I don't think commercial modems are capable of that (yet).

Just toss a doppler laser interferometer on a window, mirror, etc. At least with fiber-optics you need physical access. Single mode (I think that's most of FTTH) is pretty insensitive to vibration and hard to localize so you'd really have to install something.

So when AI takes over the world, it will have a convenient tap into every living space of every hoomin. Lovely.