The striking thing about mobile phones in American prisons is not that they exist — though they do, in great numbers — but the ingenuity used to get and keep them. There are the usual entry methods: from visitors, corrupt guards or in packages hurled over the fence. But phones often take more exotic paths. In South Carolina a potato gun was used to fire phones over prison walls from a distance of a third of a mile. In Mississippi a suspiciously heavy and bounceless basketball in the recreation yard was found to contain 19 phones and chargers.