Even if you're on the Do Not Call list, you can get phone spammers. I've got a particularly annoying one this week. They called four times yesterday, four times the day before, and now once already this morning. I'm expecting it will total four by the end of the day. I Googled the number:
(202) 652-4595 "DonorCareCenter"
It came up on plenty of those sites where people report spam phone callers. Some kind of a phony charity scam. I'm not sure why people post their complaints on those sites as it doesn't appear anyone actually does anything about the problem. From the complaints posted, it appears my best best is to ignore and never pick up.
This is why god created caller ID.