Why doesn't the "do not call" list work for these types of calls?  There are more solicitation calls from non-profits and charities & polling organizations and political parties ... they're as annoying as telemarketers and yet there seems to be no way to stop them!  What's the point then?

Keep getting calls and no one leaves a message

It was a call from AARP in NJ inviting me to a phone seminar with the NJ Director of Consumer Affairs & other officials to discuss any questions that members might have.

Received a call this morning that had just the phone number instead of a name (to get around anonymous call blocking, I guess).  I did not answer it, since I figure anyone who really wants to talk to me can leave a message.  A Google search brought up AARP-Princeton as the owner of the number.  I am a member of AARP, and I do live in the Princeton area, so I imagine it was a genuine call for either fund raising or telemarketing.  Of course, it might have been a cloned number from a scammer, and that could have been why the number rather than the name came up on the caller ID.

Received call at 2:50 pm 10/6/11; did not pick up.  No voicemail left
Call shown as:  Unavailable

I have no idea who this is.