Every carrier already knows who the spammers/scammers are based on activity…normal phones do not redial within 2 seconds of an ended call. The carriers are complicit in the scam and they need to be held to account with fines for allowing it.

This will be an unpopular suggestion here but why not just go all in on iCloud? It’s reasonably inexpensive for not data-hoarding amounts of data, reasonably secure and E2E encrypted. Given the low cost, zero setup if they’re already Apple people and lack of admin I think it is ideal for them.

I pay for iCloud storage because I want HomeKit Secure Video cloud storage (I also have a local copy on disk).