I often get cold calls; lately most of them claming to be from 3mobile. If they don't start speaking as soon as I answer, I hang up. If they say they are from a company that I know I don't deal with, I hang up. If they catch me at a particular inconveient time, they might get a f-off before I hang up.
Quite an annoying time when you're moving house and have done things like open new bank accounts and the like. Some companies numbers only show as 031xxx something so you kind of have to answer each one in case it's real.
My Great Aunt got scammed a couple years ago. She foolishly gave her CC details over the phone to some scam artist. Then realised she shouldn't have done it so cancelled her card. Worrying really, as she was a teacher for 30 years