All I can say is be thankful they don't....
Landed at IAH yesterday, and whilst we were taxing the guy 2 over from me decides he want to pre-order something from one of the restaurants in the terminal because he has a tight connection (ignoring the fact we landed 30 mins early, so it can't have been that tight).
I'm pretty sure everyone for roughly the 10 rows infront and behind us knew what he ordered. If he'd been only slightly louder he wouldn't have needed the phone as they would have been able to hear him in the terminal...