#dadtime

How do I speak to my son about body image and is it ok to call him when he's with his dad?

I have two unrelated questions today.
My son has been talking a lot lately about not liking the way he looks. He sometimes looks at the mirror and says he is ugly and the other day he told me girls at school are telling him he is short. I am not sure how to help him.
When he is with dad and I call him, he doesn't seem to want to talk most of the time.