I received a similiar call today.   After repeatedly telling "michael" that I would not give him our information.  He demanded to speak to my boss.  He got progressively more assertive as I continued to refuse his requests.  I finally informed him that I was at this point requesting that he stop calling and that I was finding the call harassing.   I then asked for his name and the company he worked for (e-secure yellow pages).   And then asked for his phone number.  In which he repeated my phone number.  When I told him that was my number he told me that I didn't know what I was talking about.  So I said fine, please hold, and then conferenced him into another line as I called "his" #.  He at that point became very irate and demanded to speak to my manager.  I told him not to call anymore and hung up.