I installed the Google Voice app (which is clearly made for iphones) on my ipad... I have a wifi only model, and when I try to text it gives me a 'not sent' error message. Am I doing something wrong, or is this just not possible? Basically I want to text using my Google voice number... I don't care about voice calls. I looked at talkatone, but it was very clunky and convoluted (especially since I don't need to call, but just to SMS) Suggestions?