Good move, it's crazy how many scam calls and SMS I receive in Australia. In fact, if I get an SMS or a call, I just assume it's a scam.
Have you added yourself to the Do Not Call register?
I don’t think this will cut down on spam so much as fraud. All spam calls I get don’t have registered IDs
The 'Ask Reason for Calling' iPhone feature has completely eliminated scam calls for me. Real callers not in contacts leave a short message and I pick it up. Best iOS feature from the last few years IMO.