Go to https://www.donotcall.gov/ this will remove your # from all call lists for 5 years. This works for land line and cell phones.
You can also call 888-382-1222. You need to call from each phone number you have to block each number.

I also called the # back and a recording said that my number will be removed from the call list in 2 biz days

I have noticed this number on my caller id several times and was finally able to answer it today.  I heard a woman's voice say "hello" and then I was quickly disconnected.  

When I called back, I heard the same thing everyone else did and like Alfred, I'm leery of putting my number in to be removed from their list.  I just added my number to the Do Not Call list but it won't take effect until next month I believe since I missed the last deadline.

So I got a call from them today and called back and got the enter your # message, I too didn't trust it.  So I decided toand start doing research on them.  That's what brought me here.  I found the National do not call list, and submitted the info.  Not five minutes later they called again.  Only this time someone came onto the line.  They are a marketing firm in connection the the Yellow Pages, Inc.  The link is below.  I told her I was going on the National Reg. and told her to put me on their list as well.  Hopefully this helps.
www.oytech.com/advertising_guide/yellow_pages_advertising.htm - 38k - Cached - Similar pages

So I got a call from them today and called back and got the enter your # message, I too didn't trust it.  So I decided toand start doing research on them.  That's what brought me here.  I found the National do not call list, and submitted the info.  Not five minutes later they called again.  Only this time someone came onto the line.  They are a marketing firm in connection the the Yellow Pages, Inc.  The link is below.  I told her I was going on the National Reg. and told her to put me on their list as well.  Hopefully this helps.
www.voytech.com/advertising_guide/yellow_pages_advertising.htm - 38k - Cached - Similar pages

ever since i got a new phone and failed to have the number not listed i'm getting calls frm them daily. when i ans. no one responds.  i called back and enterd my number and i still get calls ONE WEEK later i will now put my number on the do not call list.