I consider these calls harassment and stalking. I will be writing my US Senator and Congressman to bring this issue (and this particular number as an example) to their attention and ask that they expand the "do not call" program to include non-profit organizations. We get 6 - 10 calls a day from solicitors --some people, some computers.
As the Caller ID wasn't any more specific than "Marketing," I certainly wasn't going to answer it. I let the call go to the answering machine and they hung up. No message left.
I noticed numerous calls without a message. WHen I picked up today a woman asked for my wife by name. I said she was not here and asked if I could take a message. THe woman said "No message necessary-- have a nice day" and hung up on me. I'm waiting to see if a reverse directory search will provide anything.