Page "Integrated Services Digital Network" Paragraph 61

There are two ISDN implementations.

Basic Rate Interface ( BRI ), also called basic rate access ( BRA ) — consists of two B channels, each with bandwidth of 64 kbit / s, and one D channel with a bandwidth of 16 kbit / s.

Together these three channels can be designated as 2B + D.

Primary Rate Interface ( PRI ), also called primary rate access ( PRA ) in Europe — contains a greater number of B channels and a D channel with a bandwidth of 64 kbit / s.

The number of B channels for PRI varies according to the nation: in North America and Japan it is 23B + 1D, with an aggregate bit rate of 1. 544 Mbit / s ( T1 ); in Europe, India and Australia it is 30B + 1D, with an aggregate bit rate of 2. 048 Mbit / s ( E1 ).

Broadband Integrated Services Digital Network ( BISDN ) is another ISDN implementation and it is able to manage different types of services at the same time.

It is primarily used within network backbones and employs ATM.