All I can say is keep trying. Make arrangements to see your kids along with making those phone calls. I don't know what is going on with them, but perhaps they are angry that you and your wife are now divorced. It's hard on them, no matter how old they are.

But keep making that effort. It's better than doing nothing at all. And when you do talk to them, let them know that you love them and want to see them. But I wouldn't suggest getting your ex involved in arranging anything with them.

Good luck!