Is Google Voice free on and an Android Phone such as the HTC EVO 4G?

I really would like to know, because I hate giving out my cell phone number to every one, but I'm with Sprint and AT%26amp;T. And with Sprint, I get free calls to and from any cell phone. On the iPhone, Google Voice uses my cell minutes, and want to know if it dose that for Sprint, b/c I would rather use no minutes, and if it going to I just stick with the any mobile with sprint!|||yes google voice is free on all android phones incredible htc evo.