However if you have a business relationship with the company or one of its affiliates they are allowed to call you. This means even if you sign up for something online and give them your phone number they may call you.
At a low point in my life when I could find no other work I was one of the hated people that call you at the worst of times.
If you ask a telemarketer to put you on their do not call list they are required to do so and also to read you their policy governing the removal of your number, additionally some states are what is called a 1 no state. Meaning if a telemarketer calls one of these states if you say no they are by law required to immediately quit bugging you. I forget what states these are but I do know pennsylvania is one of them.