with what you're looking to do, the optimal scenario would be for your departmental chair to call the PD on your behalf at the place you want to go. on one level, this is one way to show a program that you're serious when you say that they're your #1 choice, because for all they know you could be telling that to five other programs, and the PD knows that someone won't be making five calls like that and colluding with you to stack the deck in your favor. furthermore, letters of rec are one thing, but a phone call is a more intimate, personal, and not meant for an audience of however many programs to which you applied but rather just this one program, and that obviously means you're serious about that program or else you wouldn't impose upon someone like a dept. chair to make such a call. for it to carry much weight, the call has to come from someone of stature--preferably someone well-known in the field and to program directors, because if the person is known then the PD at the other end of the line would recognize and appreciate the fact that this person is putting his/her reputation on the line by doing this for you, and that it would be unlikely for a "big name" in the field to put him/herself out there for you unless they believed in you and wanted to make an effort to speak on your behalf. if you've twisted someone's arm into doing this for you, this could backfire, so be careful about imposing upon someone to make a call for you. also i wouldn't do this unless you really thought this was something you felt was critical to your chances of matching at the program, because if the PD has decided you're not the right "fit" for their program, then that PD isn't going to suddenly change his/her mind because of a phone call. put yourself in the PD's shoes for a minute and ask yourself...would you like someone calling you up and telling you how to do your job (i.e. how you should rank this person over someone else)? I could see some PDs looking at those phone calls as helpful input, supplemental information if I were trying to narrow down and refine my list, but I could also see some perceiving it as someone who doesn't know my program, my program's rank list, or my applicant pool calling me up and trying to tell me why the selection committee and I might be wrong because we disagree about how we feel about the applicant being discussed (i.e. you) if they don't seem to think as highly of you as the person calling on your behalf. i think in the end it can't hurt but there's no way of knowing how or even if it will help your chances at the program. i think the phone calls that matter (if they take place) are the ones from the PD to your letter writers asking for more information, because then it means that the program is interested in you (enough so that they're calling to find out more about you), though you may never find out about those calls.
