For a few weeks I answered obvious spam calls in Korean (“yobosayo?”) and then pretended not to speak English (my Korean was barely good enough to hail a cab in Seoul, back in 1988, and it’s gone down hill since — basically I just jabbered) which was great until I got a bot that switched to Korean without missing a beat. Now I just answer “This is a non-secure line, how may I direct your call?” which is good for a quick hangup.