Microsoft KB Archive/149552

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ISDN Terms and Definitions

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Q149552

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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.

Keywords : win95

Issue type :

Technology : kbWin95search kbWin95