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.

The technology introduced in the United States and rolled out to Regional Bell Operating Companies (RBOCs) from Bellcore in April 1995, (very soon after the introduction of CLASS-based services through electronic switching system (ESS)), was marketed by the RBOCs who implemented it, as a way to streamline all available custom calling options through the use of a screen-based telephone; giving Residential and Small Business telephone subscribers PBX-like functionality at home or in small office/home office (SOHO) locations at a significantly lower cost. The service debuted before the onslaught of Personal Communications Service (PCS) and Voice over Internet Protocol (VoIP)-based telephony technologies became available and was originally slated to also work in conjunction with other types of services such as Enhanced Directory Assistance, telephone banking, movie theatre ticket sales, and other services that could interact with an LCD-screen.

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