Hey Tyler,
Listen to what the others are saying... keep calling.. keep trying. I'm not a counselor or mental health professional but I do work with emotionally troubled kids (I teach). One of the big events in the life of many of these kids is when dad or mom comes back. He might seem reluctant or hesitant talking to you right now, but my guess is that inside he's beaming.
Many is the time I've sat with a kid who proudly boasts, "I'm seeing my dad this weekend!" It's a big thing for him - but he can't tell you yet. Keep doing the right thing - you are giving a gift beyond measure - to your son and yourself!
Mike