How would the scammer communicate with you?

Phone? The network could spot sources exhibiting robocall patterns. AI could analyze live conversations and warn the recipient on certain patterns.

Instant messaging? There's spam and abuse screening built into most IMs already. AI could [locally/privately] analyze conversations.

Email? Ditto; analyze conversations, a bit deeper than basic junk mail filters already do.

I got lots of iMessage spam try to get me to contact them via WhatsApp, signal or their own website.

Unless you ban mentioning other IM platform or communication channel, they will always try to get you on something less monitored