Isdn And Bri; Pri Vs. Bri - AT&T MERLIN LEGEND Reference

Overview

ISDN and BRI

To understand the BRI option, the user should be familiar with the Integrated
Services Digital Network (ISDN) and the Basic Rate Interface (BRI).
ISDN
The Integrated Services Digital Network (ISDN) is a digital network interface
used worldwide for the transmission of voice, data, video, and other services
simultaneously over standard telephone wires. It is the leading standard in the
world for digital transmission.
With ISDN, a user can talk on the telephone while receiving and sending faxes
or data. Because it is digital, ISDN has faster and more accurate data
transmission, calling information, and more reliable establishment of calls. ISDN
is excellent for video, teleconferencing, and telemarketing.
BRI
Basic Rate Interface (BRI) is a protocol within the ISDN standard. Because it is
a station-side protocol, BRI also offers access to other groups of services, such
as central office (CO) Transfer and Local Area Signaling
features, which are described later.
While a Primary Rate Interface (PRI) line consists of 23 bearer channels (B-
channels) and one data channel (D-channel), a BRI line has two B-channels and
one D-channel. The B-channels carry the user information (including data), and
the D-channel controls the B-channel communication and initializes ISDN lines.
Each B-channel on a BRI line has a capacity of 64 Kbps, and each D-channel
has a capacity of 16 Kbps. (See Figure 1-2.)
Figure 1-2. PRI vs. BRI
o
D
PRI
23B + D
Services (LASS)
o
D
00
B B
BRI
2 B + D
ISDN and BRI 1-3