Alton_Utrich: Everyone playing in my next game, please raise your hand.
*All players raise hands*
Alton_Utrich: Not so fast late_farting_texter_pc!

More seriously I'd vote for just telling him up front that ditching game and getting distracted was obnoxious but acceptable in a casual campaign, but you're doing something more serious where that's not an option. Make sure you wish him the best in his future endeavors.