Introduction to ISDN

ISDN Introduction Integrated Services Digital Network (ISDN) is a digital version of switched-circuit analogue telephone service. It was and developed to use the existing telephone wiring system is provided by local phone companies or PTTs ISDN was specifically designed to solve the low bandwidth problems that small offices or dial-in users have with traditional telephone dial-in services. When a data call is made using ISDN, the WAN link is brought up for the duration of …

…BRI services or multiple PRIs at some sites. Once connected to the ISDN fabric by BRI or PRI interfaces, design of ISDN end-to-end services must be implemented. The BRI local loop is terminated at the customer premise at an NT1. The interface of the local loop at the NT1 is called the U reference point. On the customer premise side of the NT1 is the S/T reference point. Figure 15 shows a typical BRI installation.