I never answer the phone, even if it’s somebody I know. If it’s important they’ll leave a voice message or send me a WhatsApp.
Had a few rando’s message on WhatsApp which come from various country codes like Indonesia, Myanmar, Mexico and USA which I block straight away.
I recall last year I was watching the TV series Tehran, and in one part somebody got stuck in Iran and couldn’t leave the county and I was talking to my OH about how they could try escape to Iraq. Literally a few mins later I had an unknown number call my phone from Iran. Obvs I didn’t answer but they left a voice message which was pretty much silent but you could hear voices in the distance (couldn’t make out what they were saying). It freaked me out I turned my phone off and left it in the kitchen.