Analog Display Service Interface (ADSI)

Analog display service interface (ADSI) is a telephony standard widely used in plain old telephone service. It transmits information to be displayed on display-based telephones connected to an analog loop start line. In order for this to work, the telephone must be an ADSI-compliant device.

ADSI includes complex standard sets designed exclusively for the telecom industry. These are widely used in private branch exchange (PBX) or plain old telephone service to permit data transmissions to be displayed on display-based telephones. This technology was introduced by Bellcore and later rolled out to regional Bell operating companies in April 1995. It was then marketed to streamline available custom calling options using screen-based telephones, thereby providing small business telephone subscribers a PBX-like functionality at home for low cost.

This technology was introduced before the advancement of Voice over Internet Protocol (VoIP)-based telephony technology and personal communications services. It was slated to work with other services such as enhanced directory assistance, movie theater ticket sales and telephone banking.