my ex-wife will not give me her phone number?

[wh4t]

We have been officially divorced for 2 months, and separated for 3 months prior to that. We have shared 50/50 custody and exchange the children every Tuesday. During that week each of us have them, the other parents is allowed at least two telephone conversations, stated in our divorce papers. Her and her mother call here when I have the kids every night they are here. When she has them, I had her cell phone number, and in this 5 months she has never answered a call of mine once, an would usually call back at least one night the week she had them and let me speak to them. Now she has changed her phone provider and says I do not need her number that shell call me, which she never does the entire week, yet still calls here when i have them every day. So there is that, no top of the fact that she is starting to show a pregnancy which obviously had to have happened before the divorce was final, an will not admit to being pregnant for some odd reason. I do not have the money right now for a lawyer, so I was wondering if there are any other means of "forcing" her to allow me to have contact with the kids when she has them, an find out about this pregnancy, which could also be mine as we made a few attempts to work things out an hang out in those 3 months before the divorce was final.