Find "Network mode"
Press Apps.
Press Settings.
Press More settings.
Press Mobile networks.
Press Network mode.
Select network mode
Press GSM/WCDMA (Auto mode), GSM only or WCDMA only.
3G enables you to achieve higher data speeds than when using GSM.
If you select GSM/WCDMA (Auto mode), your phone automatically switches between the two network modes provided that you're within range of a 3G network.
If you select GSM only, you can't achieve high data speeds.
If you select WCDMA only, your phone can only connect to 3G networks.
If you select GSM/WCDMA (Auto mode), your phone automatically switches between the two network modes provided that you're within range of a 3G network.
If you select GSM only, you can't achieve high data speeds.
If you select WCDMA only, your phone can only connect to 3G networks.
Exit
Press the Home key to return to standby mode.