Right now I use Google Voice and have a Driod. I was wondering if I download the Google Voice App and send text from it, will I be using verizon's network or google's network? In other words, I don't have a texting plan and I have a data plan, so if I send a text using the Google Voice App, it won't charge me right?

I have read somewhere that the Google Voice App is integrated into the phone's SMS and Calling features so it uses the Google Voice number and not the phone number Verizon supplied me with.