Telos Zephyr, Руководство пользователя

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Section 5 ISDN 93
Zephyr ISDN Compatibility
The Zephyr’s internal ISDN interface (sometimes called by it’s generic name ‘Terminal
Adapter’) is used to connect to ISDN telephone lines. A simple menu selection easily
adapts the Zephyr to the various types of service offered by the range of central office
switches installed by telephone companies in most parts of the world. No EPROM
changes are required.
Protocols
In a perfect world, all ISDN terminal equipment would work with all ISDN lines, without
regard for such arcana as 5ESS, DMS100, CSV/CSD, SPIDs, etc. Unfortunately, the ISDN
“standard” has been in evolution for the past years and has only recently begun to settle
down. And, sadly, there will remain different standards for the USA and Europe.
The Telco network and the Zephyr communicate via a ‘protocol’ – the language
the user equipment and the telephone network use to converse (on the D channel) for
setting up calls and the like. This is where there are differences depending upon the
central office equipment used on the line and the standards which are followed. While
each will work with the Zephyr, the differences need to be taken into account when
lines are ordered and the Zephyr set up.
In the USA, telephone companies use either AT&T 5ESS, Northern Telecom DMS100, or
Siemens EWSD switches. Each of these can support the National ISDN 1 (NI- 1)
protocol standard, which has been specified by Bellcore, the technical lab jointly owned
by the phone companies. However, both AT&T and Northern Telecom had “custom”
versions of ISDN which pre- date the NI- 1 standard and some switches have not been
upgraded to the new format.
In Europe, the common standard is Euro- ISDN, following the ETS300 documents. It is
an (apparently successful!) attempt for all of the European telephone networks to use a
single, compatible protocol. The Telco authorities in most countries have adopted it
already, with most of the rest planning to do so.
The Zephyr supports all of these with the appropriate selection of the "Telco" menu, as
follows:
•
PTP
AT&T Point- to- Point Custom.
•
Natl I-1
NI- 1 from all switches; Northern Telecom "Functional" custom.
•
ETS300
"Euro- ISDN" ETS300 pan- European protocol.
In the USA, if you have a choice, the AT&T custom PTP protocol is sometimes preferred
because you don't have to trouble with the SPIDs.
CURIOSITY NOTE!
There is also a newer NI-2 and NI-97 standards, but they are
designed to be compatible with NI-1 for all of the basic
functions.