We use ABDialer. It's scripted so you click on the phone icon next to any phone number in the database and it auto-dials the phone on your desk. We use it through a T1 line, not a copper line. I have no complaints with ABDialer... works just like we need it to.
I use Skype as I have totally abandoned my specific land line use. You can see my scripts of how I integrated this on the Mac in my document repository. Just search for the the tag ronsmithmd and you'll be able to see it.