I have an 85 year old mother who lives in PA and lives alone. I did not recognize the phone number so I didn't answer but called her instead. My suggestion is not to call back and press option 2. This could open up all your contacts and personal information on your phone. Just delete it. There have been a slew of these numbers since January 1st.
they called my cell phone 30 minutes ago (incoming call was 11am ET - 9 feb 2012) i did not recognize the number and let it ring. it was callerid-ed as "unknown". they left no voice mail. these calls annoy the heck out of me.