If he texts about the game, remember one word responses. Yes, no, or it starts at 4pm or whatever. He needs to get his own damn schedule. Why the eff' do you have to provide all the times? Is he incapable?

If he wants to talk to his kids, he should send you a text letting you know when he will be calling. That way your son can answer the phone when he does call. You wont have to have any contact with him.

You don't have to have your kids call him. That's ridiculous. He's on a power trip.

The way it should go:

WAH: I'm going to call S3 at 6pm.
You: Ok

That's it! Its as easy as that!