Sprint, cell over voip

[Scooterman1]

I have a few questions, if anyone has some experience with this setup.
I have home VOIP service with Broadvoice on their Unlimited World Plus plan.
I also have their Multipresence service which allows a 2nd device/App on an Android/iPhone.
I have tried several apps (3CX, Airdroid, aSip, Sipdroid). I can get most of them to work when I'm on WiFi, but not on 3G, or 4G.
Questions:
1. If anyone has them working on Broadvoice, Sprint, and an HTC EVO (or other Smartphone), will you please post all of your settings except your User Number & Password)?
2. Do you know if Sprint has some kind of block on using Voip with 3G/4G?
3. If you have this working on Broadvoice, what App are you using on your phone?

 

[Dubl-A]

I may be wrong...

VOIP would be used if you dont have a voice plan with a cell service. Explains why you can use it over wifi.