I don't know if you guys have heard about this or not, but I'm not sure how well something like this would work in real world scenarios. Even if they knew what channels every voice network operated on in every market, this would never be able to distinguish Hangout and iMessages sent over data (unless they start packet-sniffing, in which case I believe intercepting wireless communication is still illegal). Also, how are they going to distinguish between you getting a text and sending one? Is that even possible?
http://www.dailydot.com/technology/texting-while-driving-gun/