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USA ISDN Ordering Guide
is section applies to users in Canada & USA and is intended to help you when it comes time
to order your ISDN lines. We assume you are familiar with ISDN’s basic concepts. If you have
not read the ISDN section in the manual, doing so now will help you better understand the
information that follows.
If you know who to call and you are ready to provide complete information, the ISDN ordering
process can be simple and straightforward. is guide takes you through the process step-by-
step. Telos support is always available to assist.
On one ISDN BRI circuit, there are three simultaneous bi-directional channels: two 64kbps
“bearer” or “B” channels for the transmission of user information and one 16kbps “data” or “D”
channel for call set-up and status communication. at is why this is sometimes called 2B+D
service. You can use the B channels, but only the phone companies and equipment manufactur-
ers can usually use the D channel. ISDN comes into your facility on two wires, just like plain old
telephone service (POTS).
From the perspective of telephone network routing, each channel appears to be a separate line
with it’s own number and independent dial-out capabilities. Since each has to be dialed or
answered separately, they appear to be “lines” to users also.
e Nx12’s internal ISDN interface is used to connect to digital ISDN telephone lines. It easily
adapts to the various types of service offered by the range of Central Office (CO) switches
installed by telephone companies in the USA and Canada.
Dealing with the Phone Company
As is often the case when broadcasters interface with phone people, the lines of communication
can get a little tangled.
e first order of business is to find someone who knows what ISDN is. While your usual
account agent will be the normal entry point, you may be talking to a number of phone people
before you find one who understands your needs.
Some of the regional Bell companies offer a single point of contact number for switched digital
services, while some Telcos use “resellers”. Note that in some cases the phone company will need
to do a “loop qualification” (line loss test) before they can verify that ISDN will be available at
your location.
Details, Details
Protocols
In a perfect world, all ISDN terminal equipment would work with all ISDN lines, without