The Call Screening feature is available only on PARTNER ACS Release 3.0 or later. The user must have a system telephone. This feature allows a user to listen to a caller leaving a message in his or her mailbox. A user can turn this feature on or off by pressing the programmed button. The button programmed for this purpose must have lights.
To program a Call Screening button:

Procedures
Programming a VMS Cover Button (F15)
Programming a Do Not Disturb Button (F01)
Programming a Voice Mailbox Transfer Button (F14)
Programming a Voice Messaging Auto Dial Button
(Intercom 777)
Programming a Station Lock Button (F21)
Programming a Record-a-Call Button (PARTNER ACS Release
3.0 or later) (F24)
Programming a Call Screening Button (PARTNER ACS Release
3.0 or later) (F25)