Acronym for Integrated Services for Digital Network is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. Home and business users who install an ISDN adapter (in place of a telephone modem) receive Web pages at up to 128 Kbps (Kilobits per second) compared with the maximum 56 Kbps rate of a modem connection.