An ISDN line is a digital line used to transmit high-quality digital data over a data network. An ISDN line can be used to transmit voice, data, video and other network services.
An integrated services digital network line offers many advantages over the traditional analog configuration, according to AT&T. In addition to being cost effective, an ISDN line is eight times faster than a traditional modem and is easier to maintain. An ISDN line provides capabilities not available in a standard phone line, such as sending information about who is calling and whether it is a voice or data call.