I haven't unlocked all features yet, here's the apps you can use at the moment :

CALL : Use this feature to contact your favorite NPCs for mission hints.
MESSAGE : Receive information about current tasks from friends or the guild admin.
CONTACT : Create a list of favorite contacts, with space for up to six phone numbers.
GUIDE : Display object and next area names on the map for guidance.
ALARM : Advance the in-game time instead of waiting in real time.
CAMERA : Take screenshots, useful for bug reports or for sharing amusing moments in the game. xD
BOOST : Skip the barrier animation at the beginning of battles to access battle commands more quickly.