When Obama took office in 2009, he famously agitated to maintain his Blackberry smartphone over the approved (and outdated) options. A compromise allowed him to keep it, however, the communication and capabilities were limited. He did eventually upgrade, telling Jimmy Fallon over the summer that his new device was a smartphone, but without the ability to call anyone, install apps, take pictures or play music.
The Associated Press sources now say that he upgraded to an iPhone, capable of sending and receiving emails from a limited group of people, surfing websites and reading news. Obama reportedly had a different phone used for tweeting -- one of the only devices able to access the Presidential account -- and rarely hit send himself.
For security reasons -- this is the person who controls the nuclear launch codes -- access to the president is limited, and fears of hacking put severe restrictions on available devices. It remains to be seen how the new administration will manage communications from within the bubble, but it may not be easy (we hear that maintaining one's own email server is inadvisable). For the outgoing Obama, one of his first post-presidential stops might be a cellphone store for a long-awaited upgrade.