Well, the truth is regarding the nrmp guidelines is that they can only contact you to offer information, however they choose (ie say we're ranking you #1, etc.) but cannot ask for anything.. as you said above.
The phone call means jack, and is really only to persuade you to make your choice based on that, and that way, they get to have the ego trip that they didn't have to go far down their rank list.
For instance, F.Fu from pitt calls a lot of folks 40+ to find out how they feel about the program. Their response to you saying the greatest thing since sliced bread is their program is.. we'll look at you favorably.. or in some cases "we're going to rank you to match." But that phrase "rank to match" means may different things. It could mean that they typically go 10 down in the rank list.. but have only 5 spots.. and you could be #10.. or it could mean that they ranked you in the top 5. You never know.
I have heard of plenty of stories of people whom were "ranked to match" and put the place #1, and didn't match.
On the otherhand, some places ie HSS, are more reliable in their letters and phone calls and such... You know what that means there.
Bottom line is it doesn't mean jack.. and most programs don't call. And even if you don't get a call, doesn't mean you're not going to match. It maybe that they call the middle as opposed to the top. Strategically that strategy makes sense, if you consider that those people will be less confident (as opposed to grade A candidates with interviews at all the top places, which will rank more aptly to their own choice and not where they think they'll do best) and have their decisions more easily swayed.
Oh well, another 17 days and we know whether or not we'll be orthopaedists.. which truthfully, is what matters most.