Cabletron Systems HSIM-W6 - Manual (Page 39)

Chapter 3: ISDN Line Ordering and Configuration
HSIM-W6 User’s Guide 25
In the U.S. and Canada, Network Terminator equipment (NT1) is required to provide an interface
between the HSIM-W6 and the ISDN line. The NT1 offers conversion between the two-wire
twisted pair (U-loop interface) used by telephone companies and the four-wire terminal equipment
(S/T Interface) as well as line-testing capabilities. External Network Terminator equipment comes
with a power supply (built-in or external).
In Europe and Japan, the telephone company provides the NT1 and offers end-users the S/T
interface. The S refers to a connection between customer equipment in some ISDN configurations
when a PBX is present. The T refers to the connection between the NT1 device and the HSIM-W6.
The ISDN pairs are the same wires that exist for analog telephone service. In most cases, the same
wires can be used for the ISDN line. The EIA/TIA standard for wiring is Unshielded Twisted Pair
(UTP) cable, Category 3 or above, 24 AWG (American Wire Gauge). The standard also
recommends using 8-position RJ45 jacks for new ISDN service installation. No special
conditioning is required; in some cases, conditioning must be removed.
ISDN BRI Configurations
ISDN BRI lines can be configured in point-to-point and multi-point configurations. With a
point-to-point configuration, only one device is connected to the ISDN line. With a multi-point
configuration, it is possible to have up to 8 devices (telephones, faxes, routers, etc.) connected to
the line.
Since the ISDN BRI line is used for a high speed LAN-to-LAN link, you must ensure that
additional devices connected to the S/T interface allow sufficient access for the bandwidth
requirements of the HSIM-W6.
SPIDs, Directory Numbers and Telephone Numbers
The service provider gives you up to three sets of numbers for identifying the ISDN line and
devices. You may be assigned none, one or two Service Profile Identifier numbers (SPIDs) or
Directory Numbers (DNs) depending on the service provider and country.
Phone Numbers
Numbers used for others to dial into the ISDN B channels on your ISDN line (similar to analog
line phone numbers).
Directory Numbers
Address assigned by the ISDN service provider for each device operating on the line. This number
can be similar to the phone number. The Directory Number is not generally implemented outside
the U.S.