It sounds like this is a lot of work, maybe too much to be worth it?

He may not be cheating. If you call and text him a lot, he may just want a break for a few hours. Some people need more space than other people.

I have been on the opposite end, where someone thought that I was out cheating on them because I didn't pick up their call. They called me 14 times in a single night. I wound up breaking up with him over that.

And... I've been on the other end, calling people from other people's phones. It's just not a good place to be! If you have to go to those extremes before he will talk to you, I would find someone new who wanted a similar level of contact.