ISDN

(Integrated Services Digital Network). Special connections that use ordinary phone lines to transmit digital instead of analog signals. Briefly, ISDN is a telecommunications network that allows for digital voice, video, and data transmissions. ISDN replaces the slow and inefficient analog telephone system with a fast and efficient digital communications network. ISDN lines contain two channels: a B channel, which has a 64Kbps (kilobits per second) data transmission rate, and a D channel, which has either a 16Kbps or 64Kbps transmission rate. When the two lines are used together, transmitted data can travel at 128Kbps. Compare ISDN and T-1, T-3 lines .