Do I have the right to talk to the kids over phone

[peaceSJ]

I have two kids, 6 and 8 years old. My husband and I live separately now since he insisted divorce. He has other woman. Our kids stay with one parent every other week. The thing is when the kids stay with my husband, I tried to call the kids and talk to them but my husband never answered the phone , so the kids never had chance to talk to me. Now they are traveling to other city for one week, my husband refused to tell me where he takes the kids, and didn't answer my phone either. I texted him that I'd like to talk to the kids, he didn't answer.

I feel really sad, and don't understand The reason. What should I do? Do I have the right to talk to my kids and know where they are while they are with my husband?

Your inputs are really appreciated. Thank you