Premisys 600, Справочное руководство

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Server Cards 5-5
ISDN-PRI Card Introduction
Figure 5-3 shows an application that requires 3 D channels. The user has ordered a 23B+D
facility to each of two different carriers. The third facility is a local NFAS (47B+D) connection
to the user’s PBX. In this application, the system will route calls from the PBX to the
appropriate carrier based on called phone number (see Call Routing section later in this
chapter).
Figure 5-3. ISDN-PRI Links to Two Carriers from an ISDN PBX
5.1.2.1 Network and User Side Protocols
In the example application shown in Figure 5-3, there is an important difference between the
two D channels terminating in the carrier switches and the D channel terminating in the user’s
PBX. The ISDN signaling protocol that runs on the D channel is not symmetrical. Signaling
messages are treated differently depending on whether the D channel is setup to run the
network side protocol or the user side protocol. All carrier switches run the network side
protocol, and all user devices connected directly to a network switch must run the user side
protocol. In general, network side applications cannot be connected to other network side
applications. Local routing, the exception to this rule, is explained in the next section.
Carrier A
ISDN Switch
Carrier B
ISDN Switch
IAD
CAUTION:
For
cont inued
protectio n ag
ainst fir e,
rep lace onl
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type an
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Premisys Comm
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, Inc.
Model IMA
CS/600
T 5A 250V
IEC
Fus
e
5A SB
250
V
UL/ CSA
24/48V 5A
LISTED 9K09
LR 77 063
120- 200-2
40V ~
3A, 5
0 / 60 Hz
Telephone
Equ ipm ent
Clas s 2 Po wer S
ourc e
®
®
UL
+ -
+ - + -
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VB VA
HSU-T 530 /35 S 6 0
HSU
-T
530/35 S 60
HSU-T 530 /35 S 60
HSU-T 530/ 35 S 60
HSU-T 530 /35 S 60 HSU -T
530/ 35 S 60 BRI
HSU
530 /35
S 60
P
2
P
1
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4
P
3
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CPU
CLO CK
NVRAM
W1-1
CSU
W1 -2
DSX
WA N
IF
T1+DS
1
23B+D 23B+D
NFAS 47B+D
ISDN PBX