VTech LS1850-B User Manual page 14

Steadily on when more characters are existed after the text currently
displayed.
Press to select more menu options if applicable
Press to confirm the current selection if applicable.
Press to initial an intercom call when idle.
Press to go back to previous menu level or cancel the current action
if applicable.
Press to clear a character or stop the alarm
if applicable, press to mute / unmute during
a call.
Steadily on when when you have received missed calls.
Steadily on when the speakerphone is turned on.
Steadily on when the answering system is turned on.
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