Cold salespeople are such scum. They take advantage of telephones are doorbells, which can interrupt your focus at any time, and are really intended only for people that you actually know.

Thankfully we now have caller ID and the ability to block unknown callers. Now we need the same for doorbells!

Isn't that what Ring and a dozen other smart doorbells are made for?

Don't know if that's what they are made for but screening is certainly one way I use them.

Put a no solicitation sign on your door.

I used to get bothered by Jehovahs Witnesses and salesmen, but a ‘No Solicitation’ sticker on my front door was the best improvement I’ve done to my house

Sadly, I've learned how many people don't know what solicitation means and I have to explain it to them. Sigh.