I think all this flow of numbers, can only come from the phone company itself, as you see them changing phone numbers, and there are a great many phone numbers of them. Who can afford himself to have so many phone numbers, if it is not from a phone company itself, or from a few of their employees.

Have a look at the List of reported phone numbers:
http://800notes.com/AreaCode.aspx/1-888

Called six times in a row, after I answered the first call.

Is there a way to block this?

I had that call from this # a couple of times.  I checked my call display and I just put the volume to the highest on TV (it wouldn't hurt my  hearing because I am deaf!) and held the phone receiver to TV.  I haven't received that # since!  I keep hoping!  Before I registered on the "Do Not Call" list last Oct/Nov 2008, I used to receive average 15 calls every day.  Crazy, huh?  Then in January 2009 (from 20th to 29th), then I received the calls again till I got an idea to put the highest volume on TV.  Then I hardly receive any calls except for my friends.

Called six times in a row, after I answered the first call.Is there a way to block this?

The number is for;Norsask Consumer Interviewing Services LtdI don't know why they called but it is one of their numbers in SACK.You could call your local authorities and complain. After you call them enough times they will contact the company and inform them of harassment.

The number is for;
Norsask Consumer Interviewing Services Ltd

I don't know why they called but it is one of their numbers in SACK.

You could call your local authorities and complain. After you call them enough times they will contact the company and inform them of harassment.