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Q149552: ISDN Terms and Definitions

Article: Q149552
Product(s): Microsoft Windows 95.x Retail Product
Version(s): 95
Operating System(s): 
Keyword(s): win95
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft Windows 95 
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SUMMARY
=======

This article contains terms and definitions for ISDN communications. The
following terms are defined:

  2B+D                       LEC
  Analog                     Mid-Span Repeater
  B Channel                  NI1
  BRI                        NT-1
  CO                         PBX
  D-Channel                  POTS
  Digital                    RBOC
  ISDN                       SPID
  Jack Type                  S/T Interface
  Loop Qualification         Switched 56
  LATA                       U Interface

MORE INFORMATION
================

2B+D: The Basic Rate Interface (BRI) in ISDN. A single ISDN circuit is divided
into two 64-kbps digital channels for voice or data and one 16-kbps channel for
low-speed data and signaling. In ISDN, 2B+D is carried on one or two pairs of
wires. These are the same wire pairs that today bring only a single voice
circuit into your home or office.

Analog: An electrical circuit that is represented by means of continuous,
variable physical quantities, such as voltages and frequencies, as opposed to
discrete representations, such as an 0/1 or off/on used in digital circuits.

B Channel: This is an ISDN communication channel that bears or carries voice,
circuit or packet conversations. The B channel is the fundamental component of
ISDN interfaces. It carries 64,000 bits per second in either direction.

BRI (Basic Rate Interface): The most common kind of ISDN interface available in
the United States. BRI contains two B channels, each with 64-kbps capacity, and
a single D channel (16-kbps) that is used for signaling and call progress
messages.

CO (Central Office): A facility that serves local telephone subscribers. In the
CO, subscribers' lines are joined to switching equipment that allows them to
connect to each other for both local and long distance calls.

D Channel: This is an ISDN communication channel used for sending information
between the ISDN equipment and the ISDN central office switch. The D channel can
also carry "user" packet data at rates up to 9.6 Kilobits.

Digital: The use of a binary code to represent information, such as 0/1, or
off/on.

ISDN (Integrated Services Digital Network): ISDN is a completely digital
telephone/telecommunications network that carries voice, data, and video
information over the existing telephone network infrastructure. It is designed
to provide a single interface for hooking up a phone, fax machine, computer, and
so on.

Jack Type: Different types of jacks (RJ11, RJ45, or RJ48) can be used for an ISDN
line. RJ11 is the most common type in the world and is most often used for
analog phones, modems, and fax machines. RJ48 and RJ45 are essentially the same,
as they both have the same 8-pin configuration. An RJ11 jack can fit into an
RJ45/RJ48 connector, however, an RJ45/RJ48 cannot fit into an RJ11 connector.

Loop Qualification: This is a test performed by the phone company to make sure
the customer is within the maximum distance of 18,000 feet from the central
office that services that customer.

LATA (Local Access and Transport Area): A geographic territory used primarily by
local telephone companies to determine charges for intrastate calls. As a result
of the Bell divestiture, switched calls that both begin and end at points within
the LATA (intraLATA) are generally the sole responsibility of the local
telephone company, while calls that cross outside the LATA (interLATA) are
passed on to an Inter Exchange Carrier (IXC).

LEC (Local Exchange Carrier): The local phone companies, either a Regional Bell
Operating Company (RBOC) or an independent phone company, that provide local
transmission services.

Mid-Span Repeater: A device that amplifies the signal coming to or going from the
central office. This device is necessary for ISDN service if you are outside the
18,000-foot distance requirement from the central office.

NI1 (National ISDN 1): A specification for a "standard" ISDN phone line. The goal
is for National ISDN 1 to become a set of standards that every manufacturer can
conform to. For example, ISDN phones that conform to the National ISDN 1
standard will work, regardless of the central office the customer is connected
to. Note that future standards, denoted as NI2 and NI3, are currently being
developed.

NT-1: The NT-1 (Network Termination 1) is a device that is required to connect
ISDN terminal equipment to an ISDN line. The NT-1 connects to the two-wire line
(twisted-pair copper wiring) that your telephone company has assigned for your
ISDN service. Your ISDN service will not work if the NT-1's plug is not
connected to a working electrical outlet.

PBX: Private Branch Exchange is a small version of the phone company's larger
central switching office. A PBX is a private telephone switch. It is connected
to groups of lines from one or more central offices and to all of the telephones
at the location served by the PBX.

POTS (Plain Old Telephone Service): The basic telephone service, standard
single-line telephones, telephone lines, and access to the public-switched
network. There are no added features, such as call waiting or call forwarding,
with POTS.

RBOC (Regional Bell Operating Company): There are seven regional telephone
companies that were created by the AT&T divestiture: Nynex, Bell Atlantic,
Bell South, Southwestern Bell, US West, Pacific Telesis, and Ameritech.

SPID (Service Profile Identifier): The ISDN switch needs to have a unique
identification number for each ISDN set to which it sends calls and signals. For
additional information, please see the following articles in the Microsoft
Knowledge Base:

  Q140123 Using ISDN Terminal Adapters in Windows 95

  Q148742 Troubleshooting the ISDN Accelerator Pack

S/T Interface: A 4-wire ISDN circuit. The S/T interface is the part of an ISDN
line that connects to the terminal equipment.

Switched 56: Digital service at 56 Kbps provided by local telephone companies and
long distance carriers. Similar to ISDN, Switched 56 traffic can travel over the
same physical infrastructure that supports ISDN. Switched 56, however, is an
older technology with decreasing significance.

U Interface: A 2-wire ISDN circuit, essentially today's standard 1-pair telephone
company local loop made of twisted-wire. The U interface is the most common ISDN
interface and extends from the central office.

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Keywords          : win95 
Technology        : kbWin95search kbZNotKeyword3
Version           : 95

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