as i have worked at a local isp where i'm at, we as a provider can not give out ANY information about a client to any entities without a subpoena even if we wanted to. we have to wait for the subpoena to get to us before we can release information. we got a heads up from the FBI that they wanted information about one of our clients suspected of Child Pornography, so we gathered all the info and once we got the subpoena i delivered the data over to the FBI building here. but yeah without a subpoena, an ISP will not give out info (mostly to prevent lawsuits to themselves).