Cisco SPA 504G - Customizing Your IP PhoneScreen; Changing the IP Phone Screen Contrast; Changing the Screen Backlight Settings

3. Select either the “Line activation” or “Phone activation” section, place a
check in the box next to the items you wish to activate, and press the Save
changes button.
NOTE- You will activate all of your lines at once, so if there is no
“Activate Lines” button, then you have already activated the lines.
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