I agree with mtf.  They're most probably just fishing for live numbers and everytime a person answers the phone or presses #1 or #3 to stop receiving the calls they are actually saying "yes" somebody owns this number and it's a live number.  They don't seem to be selling anything in particular to the caller but like mtf said they're probabling selling your number to more of these crooked scammers.  Unfortunately answering machines also lets them know that it's a live number even if you don't pickup.  The government needs to legislate spoofing technology.  By making it legal it's impossible to catch these jag offs because it makes them untraceable.