Generally speaking, the law is silent on the issue of the right to phone calls in the area of custody. And since custody is a state matter, each state has its own statute and case law on the issue of grandparents' rights to custody, partial custody or visitation. Absent any custody order in effect, in most states, both parents have an equal right to custody, but grandparents are not part of that entitlement. In Illinois, in order to have any rights, you need to show that not having rights to be with the children would cause them harm. But again, there is nothing in the Illinois statute that controls phone calls. As a practical matter, if the children's mother does not want you to speak with the children, she has control over them and the phone, and going to court to assert your right to do this would probably be costly and could very well be unproductive. Call your local bar association to get a referral to a reputable family law attorney, who can give you a brief consultation and explain your options and the likelihood of success. It's very sad when grandparents are prevented from being part of their grandchildren's lives, but this is not of the highest priority in custody law.