I really don't think there is a "right answer" to this question. Most of the answers are based on a few first-hand and mostly second hand experiences. I too have wanted to call some programs, but I have been sitting on my hands so far.
I do agree with HumbleMD that many PCs do not like being called by applicants. We forget that PCs are really busy with not only applicants, but they have to run the residency programs! A PC from Penn told me that she is particularly turned off by applicants who are demanding. She told me that she was especially annoyed by an applicant who stated that she should get an interview because she was given one at MGH.
However, there are numerous stories on SDN by those who claimed to have gotten interviews soon after calling a program.
I think every program is different and every PC is different. Also, you may catch the PC on a good day or a bad day.