1.4.2 Integrated Services Digital Network (ISDN)
Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher data speeds than are available with along. More broadly, ISDN is a set of protocols for establishing and breaking circuit switched connections, and for advanced call features for the user. It allows voice, date, text, graphics, music, video and other source material to be transmitted over existing telephone wires.
ISDN applications include high-speed image applications, additional telephone lines in homes to serve the telecommuting industry, high speed file transfer, and video conferencing.
In a videoconference, ISDN provides simultaneous voice, video, and text transmission between individual desktop videoconferencing systems and group (room) videoconferencing systems.