As a general point, unless I know I’m expecting an unfamiliar call, everything else not in my contacts I send to Voicemail. 99% of the time no message is ever left by these pests. If it was someone who knew you, they’d leave a message. It’s the only way to remove this distraction at the moment, until OFCOM perhaps have a rethink on allowing callers to disguise their number. Removing that ability would prevent a lot of Spam and Fraudulent calls I think. It wouldn’t stop ‘unknown callers’ but they always use to get sent to voicemail before the rules allowing disguised numbers was brought in.