I don't call my kids either. I figure his time is his time, as much as I hate it.
When I went to Texas last year for 2 weeks. I called my boys every night, they were at my Moms house and my youngest NEVER talked to me. I would hear him say to my Mom "tell her I love her" That was it. They are not phone people, didn't hurt my feelings as long as I knew they were okay I was fine.