Here is what happened last week coming into US O'Hare from Banff Canada (I do this once a month).
They ask me to turn on my phone, I do. They ask to see (hold) it, I oblige. They ask for the PIN. I say no, and add, if I am going to jail for it, let's add assault.
They give my phone back. "On your way sir, your cleared.".
Don't try that. We'll see who I get next month!