TELOS TWOX12 USER’S MANUAL
ISDN BRI ORDERING GUIDE FOR USA & CANADA
APPENDIX 7 207
the phone companies. However, both AT&T and Northern Telecom had versions of ISDN
which predated the NI-1 standard and some switches have not been upgraded to the new
format.
There is also a newer NI-2 standard, but it is designed to be compatible with NI-1 for all of
the basic functions.
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IMPORTANT TIP!
The AT&T PTP protocol is the oldest. We have seen a number of these lines that did
not allow more than one “Voice” call at a time. For this reason we highly recommend
using National ISDN 1 if your service is to be provide on the AT&T 5ESS switch.
National ISDN is widely available so this should not present a problem
SPIDs
Service Profile Identification (SPID) numbers are required in all but one of the AT&T
protocols. These numbers are given to the user by the phone company and must be entered
correctly into the TWOx12 in order for the connection to function. SPIDs usually consist of
the phone number plus a few prefix or suffix digits. There is frequent confusion between
phone numbers and SPIDs, even among Telco personnel. While the SPID frequently
includes the corresponding phone number, this is not necessarily the case.
The intention of the SPID is to allow the Telco equipment to automatically adapt to various
user requirements by sensing different SPIDs from each type or configuration of user
terminal. None of this matters with our application, but we must enter the SPIDs nevertheless.
BellSouth has proposed, and most of the other telephone companies have agreed to
implement, a standardized SPID for new installations. As of this writing, it has been
implemented by most Telcos. The standard is area code+phone number+0101
(XXXYYYZZZZ0101).
Unless you are using the AT&T PTP protocol, your Telco service representative should give
you one SPID for each B channel you order. Don’t let the phone company installer leave
without providing you with the phone numbers of your B channels (called Directory
Numbers, or DNs) and your SPIDs!
Directory Number (DN)
These are simply your seven digit phone numbers as would be listed in your local telephone
directory and will need to be entered into your TWOx12. Normally each ISDN BRI circuit
will have two DNs and two SPIDs. Each DN corresponds to a given SPID and when you
enter this information you must enter them to reflect this relationship. You may also hear of a
Listed Directory Number or LDN. This is simply the primary number for lines in a hunt
group (see below). The LDN need not be entered in the unit, unless it is also one of your
DNs.
CSD and CSV
Recall that each ISDN BRI has two possible B channels. It is possible to order a line with one
or both of the B channels enabled – and each may be enabled for voice and/or data use. Phone
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