It all depends on how important you feel about your land line.
My land line is important and I need reliability, service guarantee and longevity. Therefore I stick to the major players only (I have digital phone from my local cable provider).
I do use thrid party VOIP company (callcentric) for occasional calls when I travel in the US. This is similar to (and cheaper than) using long distance pay-go type phone cards for dialing out.
