Unknown caller.  Did not answer the phone.

Very wise! If more people would check the Caller ID, and if they did not pick up calls from names or numbers they did not recognize, there might be fewer complaints to be filed. If you do pick up such a call, and you are told to push a number, do not push a number. If you do you will immediately go on the "sucker list", and you probably will get no peace at all! Finally, report such calls to the FCC; red the forums here to learn how these reports are beginning to have an effect!

they keep calling me.

When picking up the caller almost immediately hangs up.  First call from this number today.