Find "Network Mode"
Press All apps.
Press Settings.
Press Wireless & networks.
Press Mobile networks.
Press Network Mode.
Select network mode
Press WCDMA only or GSM/WCDMA auto.
3G enables you to achieve higher data speeds than when using GSM.
If you select GSM/WCDMA auto, your phone automatically switches between the two network modes provided that you're within range of a 3G network.
If you select WCDMA only, your phone can only connect to 3G networks.
If you select GSM/WCDMA auto, your phone automatically switches between the two network modes provided that you're within range of a 3G network.
If you select WCDMA only, your phone can only connect to 3G networks.
Exit
Press the Home key to return to standby mode.