(I lurk and never post. If this is too off-topic please say so and try to forgive me)<p>I just received my new number from Google and I cant find any proof that this will not work. I set up my phone this way and if it doesn't work as planned I'll post the outcome. Also, if anyone is ahead of me on this please weigh in.<p>Many T-Mobile plans allow 5 numbers with unlimited incoming/outgoing minutes, they call this feature "My-Faves".. Program one of those 5 with your GoogleVoice number and then use that for all outgoing calls. And of course give any new people you meet the GV number instead of your original cellular number. Then switch to an appropriate lower priced calling plan.<p>Now if using GV's SMS doesn't rack up my alloted T-mobile text allowance I will be even happier!
If you've already got a data plan on your phone, you can tell Google Voice not to forward texts to your phone. Then you can just send and receive texts through the mobile app without an SMS plan.