INTEGRATED SERVICES DIGITAL
                         NETWORK

              ISDN allows a single wire or optical fiber

     to carry voice, digital network service, and video.

     Eventually, this standard will replace the plain telephone

      system.  A user will have four times more transferance

      speed than with a modem.  One of the great features is

      that the user can still use the telehone while using the

      Internet.  ISDN uses two channels, one for data and the

      other for voice.