What is ISDN?
DIVA T/A ISDN Modem Reference Guide ◆ Page 8
Connecting to ISDN - BRI and PRIThere are two types of access interfaces to the ISDN: Basic Rate Access (also referred to as
Basic Rate Interface (BRI)) and Primary Rate Access (also referred to as Primary Rate Interface
(PRI)).
Basic Rate Access
Basic Rate Interface or Access consists of two B-channels operating at 64 Kbps and one
D-channel operating at 16 Kbps. It is also commonly referred to as 2B+D.
Primary Rate Access
The primary rate interface is designed for users with large capacity requirements.
There is no single transmission rate defined for primary rate access. In North America and
Japan, for example, primary rate interface is based upon the T1 rate (defined in detail shortly)
of 1.544 Mbps. In Europe, by comp arison, the rate is 2.048 Mbps.