I don't think some of the ISP tech support departments help. I just ran some extension wiring for somebody a few days ago who had been through this with his ISP when the guy there kept insisting that the DSL modem must be plugged directly into the first jack in the house, no extensions permitted. As if another 20 ft. is going to make any difference when we're already at the end of 5 miles of wire from the C.O.
He's right, though. There is a filter has to go on the voice lines to prevent interference. If the house is daisy-chained, DSL has to be on the first outlet, so that the filter can protect all up-stream phones.
