3Com 3C10122 - NBX Business Telephone, Installation Manual, Page: 154 / 252

154 C
HAPTER
7: E1 ISDN PRI D
IGITAL
L
INE
C
ARD
Adding an E1
Digital Line Card
The following sections tell you how to add an E1 Digital Line Card to an
NBX system:
■
Preparing the NBX System for E1 Cards
■
Ordering DID, CLIP, and MSN Services for E1
■
Inserting the E1 Digital Line Card
Preparing the NBX
System for E1 Cards
Before you insert the E1 Digital Line Card into the chassis, order an E1
line, with the specifications you want, from your telephone carrier, and
have them install the line.
Ordering DID, CLIP,
and MSN Services
for E1
When you order E1 with DID, CLIP, or MSN services, 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 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. If the DDI/DID numbers match your
internal extension numbers, the translator entries in your Dial Plan can be
much simpler.
Example: You plan to use internal extensions from 100 through 299,
and the local telephone company assigns you numbers from