Just bought the Samsung galaxy tab 10.1 wifi with 3g model. If there is no wifi network available, the 3g network do not turn on. It only show no network connection even though my SIM card is inserted. Only when I reboot the device,then the 3g network is activated. Is this the device problem or the network carrier problem? Do not want to waste my time visiting Samsung service center if they going to tell me is network carrier problem Anyone can advise?