3Com NBX, Руководство по установке

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158 C
HAPTER
8: T1 D
IGITAL
L
INE
C
ARD
Adding a T1 Digital
Line Card
Adding a T1 Digital Line Card to a system requires:
■
Preparing the NBX System for a T1 Card
■
Ordering DID (Direct Inward Dialing) Services for T1
■
Enabling Auto Discover for Digital Line Cards
■
Inserting the T1 Digital Line Card
Preparing the NBX
System for a T1 Card
Before you insert the T1 Digital Line Card into the chassis, order a T1 line
from your telephone carrier and have them install the line. In some cases,
the telephone company offers T1 services only with specific, pre-defined
parameters. However, some telephone companies offer a number of
configuration choices with their T1 services.
Ordering DID (Direct
Inward Dialing)
Services for T1
When you order a T1 line with DID capability (Direct Inward Dial), the
local telephone carrier assigns a block of telephone numbers to you.
Usually, you can request a specific range of numbers, but sometimes the
carrier assigns numbers other than the ones you request.
You may be able to request that the local telephone carrier pass you a
specific number of digits for each incoming telephone call. Sometimes
the carrier does not offer any choice. In either situation, you need to
know how many digits the carrier passes.
Example: Carriers commonly pass either the last three digits or last four
digits of the number for each incoming call. Sometimes the last digits of
the telephone numbers the carrier assigns to you do not match the
telephone extension numbers you want to use for internal calls. You can
create entries in your Dial Plan configuration file to translate the incoming
numbers into the corresponding extension numbers.
Example: You want to use internal extensions from 4000 through 4999,
but the local telephone carrier assigns you numbers from 617-555-3500
through 617-555-4499. You can create translator entries in the Dial Plan
configuration file to translate an incoming digit sequence such as 3795
into extension number 4295, and a sequence such as 4213 into 4713.
The configuration would require several translator entries to handle
subsets of the total range. A unique set of entries would handle incoming
digit sequences from 3500 through 3599, from 3600 through 3699, and
each of the other sequences in which the first two digits were unique in
the range from 37XX through 44XX.