NEC UX5000 Feature Handbook page 138

Secretary Call
To answer your Secretary Call indication:
1. Place an Intercom call to the extension that called you.
To cancel a Secretary Call you left at another extension:
1. Press lit FUNCTION
Both the boss and secretary buzzer keys go out.
To cancel a Secretary Call left at your extension:
1. Do not lift your handset.
2. Press flashing FUNCTION
Both the boss and secretary buzzer keys go out.
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(Secretary Call Buzzer).
(Secretary Call Buzzer).