I had a problem with noise on my phone line, and every time I called the repair service about it, they said they would run a test on the line. Each time it took a couple of minutes, during which the phone would ring once (I was reporting the problem using a different line, since the noise was bad enough to make the problem line almost unusable).
The first time the person told me she couldn’t find a problem. The second time the person told me the test indicated that the problem was in the inside wiring. The third time the person told me the test indicated the problem was in the outside wiring.
My question is: how can they do a test from a remote office that distinguishes between the inside and outside wiring? I could understand it if there were some sort of switching or active components in the line, but isn’t the phone line from the pole to the phone just a set of wires with different types of connectors?
By the way, the problem turned out to be fairly far from the house.
Also, I don’t know whether this is relevant, but the phone line into my house is over 50 years old. It doesn’t use a modern modular installation - the phone line comes from the pole through a hole in the wall to the basement, where it ends at a terminal connector that is attached to the wall. The inside wiring is connected to the terminal with screws. It’s amazing that it’s lasted this long.