This prompted me to try and get Sprint WiFi calling working. When I approve my access point, and the address for it, it keeps saying "network connection error. Please try again" and it never works.
So I gave up on that, and tried integrating my Google Voice services with my phone for free VoIP calling. For some reason the app is only letting me text with it. This guide tells you how to make calls with Google Voice from Android: https://support.google.com/voice/answer/168520?hl=en but I am not getting the dialog screen asking me if I want to make calls with my Google voice. Whenever I call a contact it just auto rings with the normal dialer without asking.
As you can see from this picture I screen capped, my sprint recognized I have both Google Voice and WiFi calling enabled as services. http://imgur.com/qIirVrG
Not sure if this matters. But I soft bricked my phone and had to use the factory reset guide. That worked great, I even did the RTN Sprint reset to get my Sprint Spark apps back. I do currently have my phone rooted with Xposed and Tweaksbox installed.