You can set your phone to select a network automatically or you can select a network manually. If you select a network manually, your phone will lose network connection when the selected network is out of reach.
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Step 2 of 6
Press Mobile Service.
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Press Network Selection.
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Press the indicator next to "Automatic" to turn automatic network selection on or off.
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If you turn off the function, press the required network.
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Slide your finger upwards starting from the bottom of the screen to return to the home screen.