Vietnam, a police state where freedom of expression can come with a multi-year prison term, is awash in cell phones. Whether for talking, texting or taking photos, Vietnamese are buying up mobile devices at a rate exceeding the country’s own population. A sign of the communist nation’s rising affluence, it is also undermining the state’s monopoly on information. With phones available for as little as $20, ordinary consumers are buying up sets that would otherwise have been bound for foreign shores.