The window shows information about active devices, and there states. You may select devices on settings window.
Device name: Device name.
Hardware sensor: shows phone hook switch state. Not all devices have build-in hardware sensor. Most modems do not have one.
Software sensor: shows whether program picked up the call or not.
Action: describes current action.
Duration: shows how much time the action lasts.
Caller number: Caller number for incoming calls. Called number for outbound calls. Not all devices support outbound phone number detection.
Caller name: Caller name for incoming calls. The name is shown exactly as it was received by hardware. phone book is not involved.