Using Facetime with IPad 3

Celluar capability over Verizon inactive on my old IPad. Therefore, using IPad with wifi only. I'm able to use Facetime with people in my house on my wifi network, but when I try to facetime my son in Chicago, facetime is not connecting. Though he does see it trying to connect, and is able to use text feature to communicate back to me. What am I doing wrong, please? Thanks for your help!