This number calls my house all of the time.  I believe it is telemarketers, because I have also heard noise in the background when I answered it once.  Very annoying!!!

Some kind of telemarketer calling my business.  Doesn't leave message, but hangs on to line long enough for you to hear people conversing in background on answering machine before they hang up.

She is calling for donations for the Special Olympics.  Its almost to the stalking point of how many times she calls.

They call. I answer (because it is from my area). There is nobody there, no speaking. The next night, same thing.