Calls and texts are not the only things cell phones (just a minute, checking my Twitter feed...) are capable of. Drivers can also be (just a moment, updating my Facebook status...) distracted by news reading, streaming music, and (oohh! New Pokemon!!! Hold on...) games. 

Cellular service providers don't, have access to all the things a phone does.

(Check out the selfie I just took --> :) <-- ME)