what would you do

First of all, do you trust him? and if he's on a trip, maybe he needs to relax or something. If you sent him so many messages, then wait for him to answer. I don't think sending more will be usefull.
Anyways, since when did he left?

Talk to him tonight (or whenever he is getting home).

Ask him why he didnt call, he could have been busy... or something else could have been going on...

I dont think you should call him before he gets back, wait for him to call you when he DOES get back.

Calling him repeatedly will only irritate him....wait till he gets back and let HIM CALL YOU.

Blowing up his phone only makes you look clingy. It also makes it look like you don't trust him.