Carrier System : Integrated Services Digital Network (ISDN)

Integrated services digital network (ISDN) is a structured all digital telephone network system that was designed to replace (upgrade) existing analog telephone networks. The ISDN network supports for advanced telecommunications services and defined universal standard interfaces that are used in wireless and wired communications systems. There are two key user interfaces defined for ISDN networks: basic rate interface (BRI) and primary rate interface (PRI).

The basic rate interface (BRI) is the smallest transmission system (or interface) available through ISDN. BRI provides for two 64 kbps bearer channels (B channels) and a 16 kbps signaling (data) channel (D channel). This configuration is also is also referred to as 2B+D.

The primary rate interface (PRI) is a standard high-speed data communications interface that is used in the ISDN system. This interface provides a standard data rates for T1 1.544 Mbps and E1 2.048 Mbps. The interface can be divided into combinations of 384 kbps (H) channels, 64 kbps (B) channels and includes at least one 64 kbps (D) control channel.

Integrated Services Digital Network (ISDN)