Why not tell your son after he is fully awake and refreshed that daddy called before leaving on the airplane and wanted to talk to him. You fulfill your obligations to your little boy, he knows his dad wanted to talk to him and he can decide if he wants to call daddy.
I'll pass on the message, S5 is not one for wanting to call his dad.....you know how it's like pulling teeth at this age to carry on a convo. "Fine"...."Played"......
I hadn't planned on answering at all during the trip either. If he had made it a habit to call every day it might be different.
