system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I've been on the National Do Not Call Registry for awhile now.  I still get multiple telemarketer calls every week.  How do they get away with this?

Today I got a call from a telemarketer company offering discounts on cruise vacations to the Caribbean.  After she was done reading from her text, I promptly called  her a bitch, then hung up. (probably not the right thing to do, but it's satisfying)

The thing is, this wasn't a "survey", it was a direct sale.  When I picked up the phone and said hello, she specifically started out with selling a product.

I'm pretty sure this is illegal somewhere.
gpt
Former telemarketer here, 

1.      When you register on the DNC List it is only active for a certain amount of time.  After about a year you need to renew yourself on whatever website you used to register.
1.   Tell the telemarketer that you are on the DNC List.  They may be working with older information, and will have to manually take you off of their list.  
1.  Never hang up on them because YOU WILL GET CALLED BACK at a later point in time.  The meaner and more ridiculous you are the more likely you are to get called back just for the LOLs.
1.    It takes up to three months for your name and number to be considered "actively DNC."  Once every quarter is usually when the big telemarketers update their information.