After watching the news this morning about the National Do Not Call Registry I went to the Do Not Call Web Site to register. It took numerous attempts before I was able to even reach the site (later learned that traffic on the site was bogging it down). It seems to be working fine right now.
The site stated that an e-mail would be sent to verify your registration that required a response from you. The site said the e-mail would be sent in a matter of minutes.. I registered both of my phones at 10:45 am -- finally got the verification e-mails at 5:58 pm.
So if you register - be patient. It does work.