I have to agree with Hal on this one. I have a bunch of lines on my ACS at home, one pots, the rest voip. Pots line always has perfect volume, the voip lines are all different. No two have the same volume, some are very loud, some pretty soft. I had a line from comcast and when we ditched cable, that went too. It was the worst line of the bunch. It always had static on it, the volume was generally ok, but it would vary day by day. Towards the end we never used it because it sounded so terrible. I replaced it with an Ooma and it's been fine since. Fwiw, I have two Ooma's and they're both different in terms of volume. One is louder than the other, but both are acceptable. Just my two ¢.