Cobwebs that get wet at either the pole junction or internal to the house.

The inside problems I found.

But, we were having issues where the phone would cut out when it rained. DSL was worse, but would connect.

One of the techs actually came back and said "Here was your problem", and brought back a piece of wire with some of the insulation chewed. He said, while I was at it, I removed about 1000' from your telco line.

Generally, by the time the tech came out, the problem would go away. e.g. It dried out.