Recieved 2 calls today (Sunday March 18, 2012) from this number.  The first one I didn't answer personally, but my answering machine did.  The caller appeared to still be on the line, but didn't leave a message.  Recieved another call from this number about an hour later and this time I answered it.  Still no one spoke as I said hello and waited several times.  I don't understand the purpose of calls like this, other than to be an occasional irritation.