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ISDN and Ordering Issues 5
Chapter 1. ISDN and Ordering Issues
ISDN Concepts
This chapter explains several ISDN line configuration key concepts and tells
you how to order your ISDN services
Basic Rate Interface ISDN Line (U.S. only)
You will need to order one Basic Rate Interface (BRI) ISDN line from your
service provider. It will provide:
•
Two full-duplex 64-Kbits-per-second B-channels used for voice, data,
fax, etc.
•
One full duplex 16Kbps channel used for signaling.
Each B-channel can be used for a call; i.e., two calls can occur at the same
time. Services vary from individual service providers.
Note: The full 64 Kbps for each channel (called clear channel) may however
not be available across the entire communications link: many providers still
use in-band signaling (the 8-Kbps signaling is taken from the B-channel
bandwidth) so that you may only achieve a 56-Kbps channel speed.
Network Terminator
Network Terminator equipment (NT1) is required to interface between the
router and the ISDN line. The NT1 offers conversion between the two-wire
twisted pair (U-loop interface) used by telephone companies and the four-wire
terminal equipment (S/T interface) as well as line-testing capabilities.
In North America
U Interface: The router comes with only one U interface
S/T Interface : You can order the router with an internal NT1 or use your
own NT1 equipment. External Network Terminator equipment comes
with a power supply (built-in or external).