The first step is missing though. We need a caller ID for every call and text that shows who is actually calling / paying for the call. One option I think is to allow people to opt into a new phone call protocol that automatically rejects all calls and texts that are not in this new protocol where caller ID / texter ID contains the entire information.
Slowly, as more people opt into it, we can make it opt out, and then get rid of the old protocol completely. If some countries don't want to adopt the new protocol, well tough luck at that point but I think it is fundamental for us to be able to trust caller ID before we can do anything else.
I like how one of those was called the CAN-SPAM act. Others have been similar.