In-Wall|Style: 1 PackAchieve crystal clear sound from your phone connection with the DSL Phone Line Filter. This filter eliminates telephone interference within the DSL band by interrupting the signal. You need one filter for each telephone device (telephone, fax machine, or answering machine) sharing a DSL line. Installation is easy and no wiring is required. Simply connect the phone jack end of the DSL filter to the wall jack and connect the line cord coming from the device to the other end of the DSL filter. A detailed diagram is included on the back of the packaging. Do not place a DSL filter on the phone cord connected from the wall outlet to your DSL modem.