they are a bill collector

I tried to call, it was busy earlier, now it just rings and rings. Received the call initially on 09/17/13 at 4:41 pm eastern time.

on do not call list

No voicemail left, attempt to return call only results in a busy signal.

Selected one after it told me automated that it was to lower my card's interest rate.  I then asked the rep what card it was regarding as i only have 2 with no balances.  Then I said what is the name on the account they were calling about. Rep said "you pressed 1 you should know what card, visa or mastercard and it does not matter if they have balances" then I said "Excuse me" and he said "you heard me" then he hung up.  I didn't even give him my name or what two cards I have.  I'm guessing if I would have acted interested they would have wanted my ss# or card #.  In my opinion its a random # and fraud