I consider any person or organization completely ignorant if they call repeatedly, and do not leave a message.  If they don't think I will answer if I know who is calling, why do they think I will answer an unknown number?  The Do Not Call list is useless, and no one should be allowed to call cell phones.  This number will be saved in my Do Not Answer list, which has the ringer set to "Silent".  Even if this is a bona fide and legitimate charity, I don't give money to random callers!