Designed to see at a glance if lines are in use LM_24S is compatible with an analog PABX or with Centrex loop or ground start lines. Provide professional, efficient call processing at answering positions, and message centers. Provides a visual indication of the status of up to 24 telephone C.O lines or PABX stations * In-use lines show a steady LED, while ringing lines flash * adjustable common audible tone * ringing indication can be delayed for up to 7 rings * Connect up to 3 LM-24D units to each LM-24M. Enhances PABX and Centrex directed call pickup and call forward or no answer or busy features. The LM-24S system includes the LM-24M Scanner unit and one LM-24D visual display unit. The LM-24D display is Desk or Wall mountable.