There are many factors that can affect DSL performance in your house. First thing to check is that you have installed the DSL Line filters properly on every phone, fax, modem, or any other telephone device that shares the same line as your DSL.
A big factor is quality of the wiring. Using a longer telephone cord can cause a lot of problems. Test this by moving your equipment closer to the telephone jack. Secondly, most common houses were wired in a manner where all the jacks in the house are in series, running from the phone box outside to the first jack in to the house and then to the next jack and so on. So this adds a lot of splices and places for noise to be introduced onto the telephone line.
Posted in: DSL