I have a better solution. As soon as you get a spam call OR text, you can report it to your phone carrier by SMS and you will immediately get a 5-cent refund FROM your carrier.
Suddenly Carriers would fix the problem (which they totally could do with software) because instead of spam making them money, it would cost them money.
And the beauty of this solution is the FCC has the power to do that today.
Needless to say the Telecom lobby really hates this idea.