Charities, along with some Survey's and Political calls, are exempt from the DNC, however, they can still get into trouble for not placing you on a internal DNC when asked, you can also check your states laws in regards. Some states have different laws in regards to the calls, which can differ from the federal but as far as I know, Oregon is the only one that does not allow Charity calls.
Do consider maybe getting a call blocking device or phone.. You can google them and many are around $40.00 or less. If its a cell phone, some already have call blocking, if not, there are free apps on the web that will work for some. You can google this. If you have a smart phone, there is a free app called call control. Iphones appear to have apps also. Another one is called Mr. Number.
Report your callers here if they continue to call and harass:
"Venture Analytics" called me with a "Consumer Electronics Survey" and attempted to end the call after two questions. They asked if I was driving and then what state I resided in.
He then stated he had "System Issues" and attempted to end the call. I think they're trolling for working telephone numbers? He tried to send me to a website when I challenged his intentions but I suspected it to be riddled with Spyware. I refused the URL and eventually ended the call.
The caller was in a largely silent room so this may be a one-person operation. He likely identified I was not elderly and was standoff-ish, realized I was not his "mark", and found an excuse to attempt to hang up. He spoke English as a First Language and sounded American with no obvious regional accent.