Um.... Not quite, Magilsugam...
Kingdom Hearts: Coded is for some uber-advanced cell phone (remember, the cell phones in Japan are much more powerful than American cell phones) and takes place AFTER Kingdom Hearts II. Pretty much Jiminy Cricket is hanging out, looking through his old journal entries and he notices an entry he did not write (or doesn't remember writing). Jiminy then digitizes the contents of the journal and creates a Matrix-like computer world in which they must figure out the cryptic message (all the while hanging out with an AI version of Sora).
Kingdom Hearts: 358/2 Days is the Nintendo DS-exclusive prequel to Kingdom Hearts II that deals with the year or so that Roxas existed (remember, Roxas was created the moment Sora temporarily became a Heartless during the events of Kingdom Hearts I). It follows his missions while working with Organization XIII, but also deals with a strange, XIV member of the Organization that either wasn't around in Kingdom Hearts II or we didn't see.
Kingdom Hearts: Birth By Sleep is a PSP game and is a PREQUEL to the entire Kingdom Hearts series. It takes place 10 years before Kingdom Hearts and follows three friends: Terra, Ven, and Aqua. They are all apprentices to a Keyblade Master, and the have a scenario-based adventure dealing with some sort of enemy called "the Unbirth", which are neither Heartless nor Nobody.