Matrix Telecom SIMADO GBR42 System Manual page 90

Matrix
passive bus configuration. In case of short passive bus
configuration, eight TEs can be connected to a single NT on a bus
up to 200 meters. In extended passive bus configuration, multiple
TEs are grouped together at one end of a bus, up to 1 km from the
NT.
• Although only two B-channels are available at any point in time,
numerous other calls can be put "on hold" via D-channel signaling,
a feature referred to as "multiple call appearances".
• BRI can be used in small offices to support all of its voice and data
communication requirements. In a larger office, one or more BRI
lines can be divided among multiple users and applications via a
server or a PBX.
Primary Rate Interface (PRI) ISDN
• To support higher bandwidth requirements, ISDN is also available
in primary rate or PRI (Primary Rate Interface). This service differs
depending upon the region where it is deployed. In North America,
Japan and Korea PRI supports 23B channels and one 64 Kbps D
channel. In the rest of the world it provides 30B channels and one
64 Kbps D channel. These are referred to as 23B+D and 30B+D
respectively.
• A PRI line consists of thirty B-channels, which can be viewed as
thirty logical pipes supported by two D-channels as shown below.
One of the D-channel is permanently used for framing,
synchronization and other administrative purpose. Hence, the user
has access to only D-channel for signaling.
ISDN PRI Service
• Unlike BRI, PRI does not support a bus configuration i.e. multiple
devices cannot be connected to a PRI line. However, a PBX can be
used to reallocate PRI resources.
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B-Channel
D-Channel
SIMADO GBR42 V1 System Manual