Specifications

Reference Guide
2-25
Applications ISDN Primary Rate Interface (PRI) Server
Figure 2-13 shows that three customers are subscribing to ISDN services. Each customer is
using a fractional PRI service. Each customer could be directly connected to the ISDN switch,
which would consume three fractional T1/E1 circuits, and three D channels. Instead, the 3
fractional ISDN circuits are connected to a PRI Server equipped IAD. The PRI server grooms
the B channels in the three fractional ISDN circuits into one circuit. It also grooms the three
D-channel circuits into a single D channel that is routed to the switch. The IAD benefits in this
application include saving on back haul costs, switch port costs, and switch system resources.
Figure 2-13. Fractional PRI Provisioning using an IAD
2.6.3 ISDN Video Conferencing and Video Broadcast
This integrated access system is used to connect video conferencing equipment to an ISDN
PRI line. In Figure 2-14, a video CODEC is sharing a PRI line with an ISDN PBX. The system
is simultaneously routing calls on a call by call basis to either the PBX, the CODEC, or out to
the network. The video conferencing equipment can be connected via an RS-449 connection
with an RS-366 dialer or directly to the IAD via an ISDN PRI interface. A connection to the
IAD via the RS-449/RS-366 combination would require the use of a switched HSU card in the
IAD.
Figure 2-14. Video Conferencing System and PBX Sharing a PRI Line
23B+D on T1
30B+D on E1
Customer 1
10B+D
ISDN
Switch
IAD
Customer 2
7B+D
Customer 3
5B+D
CODEC
PBX
PRI
IAD
ISDN
Provider
PRI