Has called 4 times and hung-up 4 times

I answered.  (lots of background nosie) The guy said "Good Morning, can I speak to Mrs. abc".  I said "speaking, who is calling".  It went silent (no background noise) for a moment.  I said "Hello?".  The guy hung up the phone.

Called my home number @ 19:57 on Apr 10, 2008. I picked it up on the third ring, no one was on the other end after 3 seconds from me picking up, so I hung up. I'm in Hamilton, ontario

I get several calls from (416) 646-8001 each week and this has been going on for many months. They do not leave a message and I suspect they are selling someting.  When I call them back no one responds.  Most legal companies will at least answer the phone so that a request to have my number dropped from the list can be made.  Who are these people?  Nothing shows-up in reverse directory.  Where and how can the general public get action against this type of caller.

The f***#$s keep calling me. When you call back there is busy signal.Send in the army and smash these b***hes!

I also have been getting calls every day for about 3 weeks now.  I called back and got 2 quick rings and a busy signal.  I don't think this number is in service but something definitely wonky is going on here...