It remains to be seen how well this will work nationally. Accessing a steady, reliable phone signal is still dicey across huge areas of the country.
Even major cities like New York still have a surprising number of spots where you can't get a signal. In most places, Wi-Fi remains a dream. For many miles of rural track, particularly out west, iPhones may be all but useless to conductors for accessing real-time ticketing, reservation, and passenger information.
Cell phone towers also don't fare well in the face of major storms and tornados. And as New Yorkers discovered in 2001, a sudden catastrophe can trigger such a heavy call volume that the system is overwhelmed.
There's much to be said for retaining simple, 19th century "paper ticket and puncher" technology. It will always work, regardless of what's happening outside the train.
Plus it requires no batteries. It isn't prone to computer glitches. It won't break or malfunction if dropped on a train platform. And it's less apt to be "acquisitioned" by a nefarious passenger (or Boy Scout) whenever an Amtrak crew member forgetfully leaves the expensive device on a cafe car table or in a rest room.