Out of town husband

My husband has a job where he goes out of town mon-fri. for a while i noticed many things about him.

He doesnt call me as usual, and when he does its always really late between 10-1 sometimes when he calls me or i call him i always hear an echo in the background.

Hes also changed towards me like always mad or irritated or restless the only thing that hasnt changed is our sex lives which is what worries me b/c it makes it hard for me to prove my suspicions since hes ALWAYS horny and ready.

For example today i called him @ 1:30 am when he answered he was very surprised and his voice sounded agitated (i hardly rarely call him he calls me)he said he was still working but he was very quiet then his phone cut out and i kept getting his voicemail he called back 7 minutes later saying his battery died and he had to hook it up in the car which by the way he always claims he never takes.

I dont really know much about what he does when hes out of town cause i dont ask and he doesnt tell i do know he stays in motels and eats out every night.

So these are just some things i have noticed but i am unsure if its just me or he really is cheating this time.

Now also i should inform you that i am a very insecure person and have mostly accused him of cheating so he may have gotten smart about it b/c he doesnt cover his cellphone and his computer usage is rare so whats goin on?