First of all, was there any kind of ID aside from the number? That would be very helpful for you to report. Secondly, what do you consider elderly? Mine is 95! and there is no answering machine, caller ID or voice on phone so if she answers and get no immediate response, she automatically hangs up.
got it too ... wanted credit card for shipping and handling of rebate cards ... also wanted identifying info ... gave them neither ... of course a scam - don't answer