This chapter provides you with  some background information about ISDN, including information about: • analog vs. ISDN • type of ISDN service •ISDN l ayer s • ISDN bearer capability • services and features  for ISDN PRI and  BRI • ISDN hardware • ISDN standards compatibility Integrated Services Digital Network (ISDN) technology provides a fast, accurate, and  reliable means of sending and receiving voice, data, images,  text, and other information through the telecom network. ISDN uses existing analog telephone wires. The signal on the wire gets divided into separate digital channels, which dramatically increases the bandwidth. ISDN uses a single transport to  carry multiple information types. What once required separate networks for voice, data, images, or video conferencing is now combined on to one common high-speed transport.