It's the year 2257. Our Heroes- Sulu, Chekov, Kirk, McCoy, Uhura, Kyle, Riley, Joe, Gaila, Cupcake, Christine, Ensign Ricky, the whole lot- are all cadets at Starfleet Academy. The rest of Our Heroes- Spock, Giotto, Pike, M'Benga, Scotty if you don't mind breaking canon a wee bit and saying he got exiled less than a year before the movie- are instructors.
Even though it's supposed to be against the rules, everyone gets bored and starts commtexting each other in class. Their various instructors, of course, catch them and join in the fun.
Okay, 3, 2, 1, let's go!