My contract with AT&T ends in about 12 days and I have considered not renewing it. If I just wanted to use Google Voice and the app (GV Mobile +) on WIFI, will this work? Can people still call me if I only have that on wifi using my Google number? I know I can call out...but in bound is what I am worried about. I have a Gizmo account too for my computer if that even factors. Thanks for your help.