The caller had used a Private Number
I have set a general block on private numbers, if anyone needs to hide their number then I probably dont want to speak to them.
I also enable Caller ID spam protection, I have a Samsung S22. This refers any numbers not in your contact list to an external database, and identifies incoming calls as 'Potential Spam' or 'Potential Fraud' if appropriate. Obviously if the call is identified in this way I dont answer it.
This has reduced scam/spam calls to a trickle, the odd one still gets through but overall its maybe 1 a month rather than several per day. This is why we dont have a landline phone connected, its much easier to filter out the rubbish on a mobile.
My email spam filter seems fairly good, again the odd one get through. One thing with any email is to learn how to read the header, not the name that is displayed, but the actual URL of the sender, as this usually give a clue