Should My ex allow me to talk to my daughter on her cell?

My ex-husband bought our 8 year old a cell phone so that he may communicate with her more often. I have no objection to this except that the phone is restricted to a limited amount of numbers that are allowed to call and my number is not one of them. I have asked that I really would like to also be able to call her on her cell phone but he claims that if I want to do that then I need to pay for half the bill, if not I can call his number anytime and talk to her. I would like for an honest response as to who is right here? Should I have to pay to be able to talk to my kid on her cell? or is he being selfish? thanks