said by SilverSurfer :

To which I'm guessing you and everyone else who still receive sales calls are most likely still getting them for 1 or 2 primary reasons:

1 - You have an "existing relationship" with the company, whose definition is pretty broad. All that is necessary is to say company XYZ has an existing with you is that you purchased something from the company and/or you spoke to them on the phone.

2 - You haven't learned not to give out the protected number. Personally, I guard my # as zealously as I guard my SSN. I can tell you exacly who has my number and they're either friends/family. I make it a policy to never, under any circumstances EVER disclose my # to a company even if they promise not to sell/trade it.

If you aren't protecting your do not call #, then it is inevitable that at some point, you're going to get a sales call. You have to be vigilant about protecting your data specifically because although the do not call list exists, money still buys loopholes in the law. And if you're a multibillion dollar corporate entity, you've purchased a few politicians to ensure those loopholes in the law exist. That is why the default for consumers is they are forced to jump through hoops in order to Opt Out.