Telos Zephyr Xstream, Руководство пользователя

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USER’S MANUAL
Appendix 8 – Ordering ISDN for the USA and Canada 331
Appendix 8: Ordering ISDN for the USA & Canada
This 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 have read the description of ISDN in section 7 (ISDN
Basics) and are familiar with ISDN’s basic concepts. If you have not read that section, doing so
now will help you to better understand the information that follows.
Because ISDN in the USA is complex, there is occasionally confusion about what it is and how to
get it. If you know who to call and provide them with complete information, the ISDN ordering
process can be simple and straightforward. This guide takes you through the process step ‐ by ‐
step. Telos Technical Support is available to answer any further questions you may have. Don’t
take “no” for an answer if your Telco does not understand your needs.
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. That is why this is sometimes called 2B+D
service. You can use the B channels, but only the phone companies and equipment
manufacturers 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 its own number and independent dial ‐ out capabilities. Since each has to be dialed or
answered separately, they appear to be “lines” to users also. We refer to a B channel as a “line”
on the Zephyr Xstream’s menu.
The Zephyr Xstream’s internal ISDN interface (sometimes called by its generic name “Terminal
Adapter”) is used to connect to digital ISDN telephone circuits. 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.
Ordering ISDN
Dealing with the Phone Company
As is often the case when broadcasters interface with phone people, the lines of communication
on ISDN can get a little tangled.
The 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 might be talking to several 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.
Here are some contact numbers we use – if you have particularly positive or negative
experiences with these offices, please let us know.