3com SuperStack 3 NBX Manual De Usuario

You can configure the T1 Digital Line Card to use one of two types of 
signaling:

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DS1 protocol (sometimes referred to as “Standard T1”)

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ISDN PRI (Primary Rate Interface) signaling

The system provides E911 (emergency) connectivity if the T1 Digital Line 
Card is configured for ISDN PRI (Primary Rate Interface) signaling. The 
system provides the calling number (ANI) so that the emergency services 
personnel can determine the location of the caller from the E911 
database. You must update the CO (PSAP) databases.

Adding a T1 Digital Line Card to a system requires these procedures:

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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.

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.