1. Find "Additional settings"
Press the phone icon.
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Press the menu icon.
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Press Settings.
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Press Calling accounts.
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Press the name of the SIM.
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Press Additional settings.
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2. Turn call waiting on or off
Press the indicator next to "Call waiting" to turn the function on or off.
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3. Return to the home screen
Slide your finger upwards starting from the bottom of the screen to return to the home screen.
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