Who's got two thumbs and a Secret Service-approved phone to tweet from? On arriving in Washington on Thursday ahead of his inauguration, Donald Trump has handed in his Android device in exchange for an unidentified locked-down phone, according to Associated Press. From a report: The phone comes with a new number that is known only to a limited number of people. This marks a big change for Trump, who's frequently on the line with friends, business contacts, reporters, foreign leaders and politicians. Barack Obama was the first president to use a mobile device approved by security agencies because of hacking concerns. Initially he had a heavily modified BlackBerry and later switched to another phone that had most features totally disabled. He was not known to use it for making or receiving calls, but it was one of few devices that had access to the @POTUS Twitter account.