Sometimes I answer the local # too, except I say nothing and put them on speaker. Listen carefully, if it is a robo or telemarketer the background is waiting for your voice to activate either one. Since I never say a word, there’s no voice activation....it times out. Many times that ends it for good.
With our landline, we let Ooma take care of business. With our cell phones, if I don’t recognize the number I answer, wait a few seconds, then hang up. That way, I don’t end up needing to call into voicemail and wasting my time just to find out it was a garbage call. One time in the past year, I had a repeat call, and it ended up being legit. That number is now in my contacts list.