Static on the phone line is generally caused by a short in the phone wiring, or damage to the wiring causing some of it to be exposed to the open air. It can also be caused by a malfunctioning phone. Check all of the phones in your home. If only one is having the static problem, it may be malfunctioning, or it could be a problem with the specific wire that runs from it to a wall jack. If all of your phones have static, there may be a problem with either the phone wiring in the walls, or the line that runs from the back of the MTA to the wall.