The Busy Lamp Field (BLF) feature allows you to configure a key to monitor another extension, answer a call ringing at the monitored extension and also dial the extension directly with a single key press.
If you have an XSTIM phone, you can program a Ringing BLF or a Non-Ringing BLF key.
To have a visual indication only when extension xxx is ringing, configure xxxB in the Digits field and enter an appropriate Label.
To have your phone ring when extension xxx is ringing, configure xxxR in the Digits field and enter an appropriate Label.
To configure a BLF key via the phone's web interface: