The CIS Secure DTD-ATTEL-XX Analog Phone is based on the Cortelco 250044-VBA-27M Desktop and 255444-VBA-20M Wall Mount telephone. Traditional and uncomplicated, the analog Wall-Mounted and Desktop Phones hook directly up to a plain telephone line. There is no special setup of extraneous power sources required. The DTD-ATTEL-XX is virtually the same as any other touch-tone phone, the only difference being the additional of the Positive Disconnect On-Hook security. The analog phone is set to automatically disable the On-Hook security when the handset is picked up. The phone also allows the On-Hook security feature to be engaged while in a call, providing enhanced “Hold” and “Mute” security. Once the handset is placed back On-Hook, the security will engage automatically.