If you knock on the door of a house posted "NO SOLICITORS" to make a sales pitch, you might be arrested, and properly so.
If you call a phone number posted on the Do Not Call list to make a sales pitch, you might be fined, and properly so.
End of argument.
Agreed. But where in the Constitution does it state that the government in the business of making NO SOLICITOR signs? I completely agree I have a right to post a no solicitor sign on my door if I like, and to enforce it. But what business is it of the government's whether I do or not?