For those who has poor line quality and still cannot fix it, I recommend to use Zyxel ADSL modem/router. My attenuation downstream is 59.0 db and I still can get SNR at 17.5db at 1M/512K line. no DC at all, even the thunderstorm strikes also no disconnection. compare to my previous Aztech ADSL, the zyxel is much better than Aztech.