Analog Display Services Interface

Analog Display Services Interface (ADSI) is a telephony technology that is used in plain old telephone service (POTS) or computer-based private branch exchange (PBX) telephone service. It works in conjunction with a screen-based telephone ("screenphone") or other compatible customer-premises equipment (CPE) to provide the user with softkey access to telephone company or internal PBX custom calling features. It is an analog service because it uses analog frequency-shift keying (FSK) technology to interact with an LCD screen via short, low-baud rate, downloads to refresh and re-program softkeys in real-time.