Interphase Tech iSPAN 5535 PRI - Manual (Page 146)

Primary Rate Interface
126 Interphase Corporation
Each ISDN B channel can be used separately to allow two
different connected users at the same time. The ISDN B
channels can also be combined to provide a total bandwidth of
128 Kbps.
Primary Rate Interface
The ISDN Primary Rate Interface, like BRI, has one D
channel, but it has more than two B channels. The number of
B channels for PRI differs from the United States to Europe.
• In the United States and Japan, PRI consists of 24
digital channels: one D channel and 23 B channels.
• In Europe, PRI consists of 31 digital channels: one D
channel and 30 B channels.
These channels can all be used simultaneously, and are often
referred to as 23B+D (for the United States and Japan) or
30B+D (for Europe).
Each ISDN B channel can be used separately to allow multiple
connected users at the same time. The ISDN B channels can
also be combined to provide a total bandwidth of 1920 Kbps
for Europe, or 1472 Kbps for the United States and Japan.