I would add, if you do answer the phone, don't say "Hello" or anything like that. The automated callers are looking for hints that someone is on the other side of the line and give up easily to get to the next number, where a person would usually spend a couple of seconds to check if someone answered the phone properly.
Nowadays if I pick up to a silent line I usually just hang up.
Yeah, I usually answer and put the mic on mute to see if there's anyone on the other end. Usually it's a robot waiting for audio from the other side to proceed, so it hangs up after several seconds without ever saying anything.
That's kind of a dick move to normal people that are calling you because making the caller say "hello?" first is the complete opposite of the normal flow.
Nowadays if I pick up to a silent line I usually just hang up.