bwnbwn - 8:54 pm on Aug 16, 2011 (gmt 0)
I agree with all the other good post but actually there is a way with just a toll free number that isn't trackable. It will be a month behind though but better than nothing. Set up a new number then when the monthly bill comes in all you need to do is see how many calls came in, get the average time a salesman is on the phone with a sale, and you can get pretty close.
You still in the dark on some important data but this will at least give you something to go by on conversions. The conversion page URL can be were you put the new number only available through an adwords ad.