The SR-1 will generate loud ringing from an analog ringing line or from a dry contact closure. There are 4 different ringing sounds to choose from. Loudness is easily adjusted with a volume control and test button. The SR-1's unique sounding rings are useful for employees that often work away from their desks, allowing them to instantly recognize when their phone is ringing. A second set of contact inputs will trigger a door chime (doorbell) sound. This can be used to notify that a door has opened or used as a door bell or push for assistance button. The SR-1 is easy to install and comes complete with a power supply and connections for an optional external speaker.