I don't really know who calls from this number, but their voice mail says that they call on the behalf of non-profit organizations, and, if this is true, it would just prove the old axiom: that no good deed goes unpunished.

You donated to some charity, and for that they sold/ traded your name and phone number so that you could get calls from unknown people asking for money.

This call comes in daily. Received 5 incoming calls from this number within 2 days. No message.

They have called at least once daily for two months...we never answer.  Slow learners.