ISDN

Integrated Services Digital Network. Set standards for the transmission of digital voice, video, data, and other signals through the traditional copper wire telephone service used by the Public Switch Telephone Network (PSTN). ISDN is credited as an early high-speed Internet service that has since been replaced by DSL and modern cable service. In this kind of network, there are two service levels: Basic Rate Interface (BRI) and Primary Rate Interface (PRI).