That's probably the worst solution to the problem. IMO, the solution is to have an app that can screen messages based on user-reported spam score. The reason

That's probably the worst solution to the problem. IMO, the solution is to have an app that can screen messages based on user-reported spam score. The reason phone companies shouldn't do it is that it is very unlikely they will do it well. There is still going to be a lot of spam and it is more than likely there is going to be a huge number of false positives that will not be possible to circumvent.