Individual called my business and asked for my mother-in-law, then promptly hung up on me before I finished explaining that he had called a business.  Rude in the extreme.

They keep calling any day, any time and hanging up.Who are they and what do they want?

They keep calling any day, any time and hanging up.
Who are they and what do they want?

continues to call and does not leave a message

Calling multiple times daily, no messages. As Kingkong says, the message at their end claims that they are a fund-raising service for non-profits. But a classless one, apparently.