I have Verizon for both phone and DSL. Today my phone line had so much static it sounded like the person on the other end was scrunching up packets of crisps. My DSL was also really flakey, I kept getting 100% packet loss.
I call them up and log the problem. The engineer calls me back and tells me the line test shows there was nothing wrong with my line and the static has now gone away. If it comes back they'll send somebody around but if they can't find a problem I have to pay for the callout.
Fantastic. Knowing my luck, the static is caused by somebody in my apartment block doing something strange and they'll stop doing it as soon as the engineer comes.
The worst kind of problem is an intermittent one.