I just received a voicemail from this number and it left a partial message of lowering interest rate or whatever...then I came here and googled the number, because no one is going to contact you by phone to lower your interest rate. All of those offers come through either the mail or direct contact with the bank. I think I will report the # as suggested here. If nothing else, it certainly is a nuisance.
If you want to go through the hassel (or principle) of pressing charges for continuing to bother you once you've asked them to put you on their Do Not Call list, you can win a settlement of anywhere from $400 to $500 from the annoying caller.