The best thing you can do to improve your odds is to make improvements to your cover letter and resume. There are two reasons people get rejected. First is they are not qualified, which there is not much you can do about. The main reason most people are rejected is their materials are poorly prepared or do a poor job of "selling" their skills. Every cover letter and resume should be written individually for each job opportunity. You are not getting rejections because you did not call.
I have chaired a search committee and been on several others. A call from a candidate up front would do nothing to convince me they should make the first cut. Before candidates are contacted the only thing that matters is if they are qualified. Their interest, communication skills, etc. comes into play once the ideal candidate pool has been determined. Often a call from a colleague of someone on a search committee that knows the candidate and can testify to your skills does a positive effects. I know when I got this job an informal conversation between someone at my past employer and my current employer did help me to get an interview.
I have been told by some colleagues that such calls may actually turn them off to a candidate. I am not sure why and I do not think that way.
Brian C. Gray
Head of Reference & Engineering Librarian
Kelvin Smith Library
Case Western Reserve University
http://blog.case.edu/bcg8bcg8@case.edu