This was the 30s, with phone lines decades? older, so would they even be waterproof? I guess they could use asbestos and wax or something, but this was before wide scale platic.

Rubber coated maybe?

I guess my point is, that you could tap into the line without breaking it. And rubber coating on a wire after a decade in the sun, would have lots of cracks?

Again, these wires would be a decade or more old. 1900 tech? Would they even be coated?

Few people even had phones. Party lines for a whole rural town were common. And you could separate lines with spacers.

Anyhow. I think they just tapped into the wire.

Maybe they just slapped some liquid rubber after tapping?