1. Loop: 5 2. Telephone sets should be TONE dialing only. 3. CO Dialing Tone - continuous Internal Dialing Tone - continuous (450 Hz) Internal Ring Back Tone - 1 sec. ON, 4 sec. OFF (450 Hz) Internal Busy Tone - 0.35 sec. ON, 0.35 sec. OFF (450 Hz) Internal Confirm Tone - 1 sec. ON (450 Hz) 4. Power : 120V / 220V