Hi All; I live in LA area and travel back and forth to Shanghai, Tokyo and back. I recently purchased iPad2 stock with 3G (AT&T) and WIFI but did not get the service. When I arrived in Shanghai, I turned on the iPad and China Unicom signal was detected very strongly but did not connect as it requested vpn, account, user name and password. Does anyone know if I can just use the existing sim card that came with the iPad2 with the right account name? Can I get this from China Unicom?