Which mobile carrier platform was Kingdom Hearts coded released for?

Kingdom Hearts coded was released for the NTT docomo mobile-phone platform.

Coded was a Japan-only episodic Kingdom Hearts game designed for mobile phones rather than a traditional home console. It was developed by Square Enix with Disney Interactive Studios and followed the events of Kingdom Hearts II. The story takes place inside a digital reconstruction of Jiminy Cricket's journal.

The game was first released pre-installed on the Docomo PRIME Series P-01A phone. Its episodes appeared over time, beginning with a preview in November 2008 and continuing through eight main episodes released from June 2009 to January 2010. Technical demands limited the planned expansion to other Japanese carriers and the United States.

Players outside Japan generally encountered the title through Kingdom Hearts Re:coded, a substantially reworked Nintendo DS version. That remake helped make the story more accessible internationally, but it does not change the original platform answer: the first coded release belonged to NTT docomo.