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A4
Euro-ISDN Ordering Guide
is section applies to users in Europe and other countries where the Euro-ISDN ETS 300
standard is supported (much of South America, Mexico, etc). Since there are virtually no
options when ordering Euro ISDN this section is probably not needed, however we thought we
could help out by summarizing what you will require.
If you live in a country outside of North America which does not support Euro-ISDN, your lo-
cal Telos Systems representative should be able to provide you with information about ordering
(and using) ISDN in your area. We assume you have read the description of ISDN in section
2.3 and are familiar with ISDN’s basic concepts. If you have not read that section, doing so now
will help you better understand the information that follows.
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. We refer to a B channel as a “line” on
the TWOx12’s menus and LEDs.
Details, Details
Names
We’ve seen Basic Rate Interface ISDN called by a number of names. e term “S0” is sometimes
used as a technical term for ISDN BRI. Of course the term “BRI” is also used, mostly by
Telecom technicians. e most common term we’ve seen in Europe is “ISDN-2”.
Multiple Subscriber Numbers (MSN)
ese are simply your phone numbers. e number of digits will vary depending on your area.
Normally each ISDN BRI circuit will have three MSNs. You will be using only two of them for
each ISDN BRI circuit, one for each B channel. e LDN need not necessarily be entered in
the unit (although it would be if it is also one of your MSN’s).
CSD and CSV