The best thing to do is not answer - period. Block the call if you can. But once you answer they know they have a good number. Asking them to put you on their do not call list is a joke. If they were legitimate and you are on the national DNC list they wouldn't call in the first place.
Repeat caller whose number had previously been Blacklisted called on 10/09/2014 @ 06:03 PM from Frederick, MD. The phone was silenced.
The caller hides behind the V number on Caller ID. V numbers change ever second as the time changes.
I am forward all Maryland calls to my number to Representative Elijah [***]'s office. Because he won't bust the IRS harassing 501(c) 4 groups, and it is calls from his state.
My daily call from Frederick, MD on 10/11/2014 @ 12:40 PM. My phone silences the ringer but I'm tired of posting for this number. One more call and they get on the Optimum block list. Then the call is blocked before it gets to my home and I'll be done on this thread.