- 2B+D
- Basic Rate ISDN line configuration: Two 56/64 Kbps bearer channels (or B-channels) for customer information and one 16 Kbps delta (or D-channel) for signaling.
A
- Appletalk
- Apple Computer 's networking protocol that can transfer data at speeds up to 230 Kbps. Requires minimal configuration.
- AT&T® "5ESS" (Electronic Switching System)
- The name of a central office switch manufactured by AT&T. These switches use Custom (proprietary) or National ISDN-2 (NI-2) software.
B
- B-Channel
- 56 or 64 Kbps-capable bearer channel.
- Bandwidth Allocation Control Protocol (BACP)
- The set of rules that manage bandwidth over PPP dynamic multilink connections. This enables you to control the number of B channels you use (i.e., cost) depending on your bandwith requirements.
- Basic Rate Interface (BRI)
- Standard ISDN line comprised of 2 B-channels and 1 D-channel.
- Bitsurfr/Bitsurfr Pro
- Terminal adapters manufactured by Motorola. The Bitsurfr is only capable of a single 56 or 64 Kbps connection and only has one analog (RJ11) port. The Bitsurfr Pro is capable of bonding or aggregating 2 B-channels for 128 Kbps maximum speed connection and has two analog ports.
- BONDO
- Proprietary multichannel bonding protocol used by Zyxel for connecting two of their Terminal Adaptors.
- Bridge
- A device connecting two or more similar networks at the Data Link layer. A bridge is generally more simple and less costly than a router, but is constrained by the amount of information it can transfer from one network to another.
C
- Call Bumping
- Method by which a 2 B-channel connection gets dropped down to a 1 B-channel connection when there is an incoming call or when the handset is picked up through an analog device connected to the TA. Southwestern Bell currently supports outgoing "call bumping", but not incoming.
- Central Office (CO)
- The telephone company's local facility providing telephone service in your area. Likened to a node or hub. If the distance between your location and the central office switch exceeds 18,000 feet and/or the signal loss exceeds 35.0 dB, a repeater must be installed to allow ISDN service.
- Centrex
- A service offered by a Central Office, providing a virtual PBX to a set of extensions. It includes features such as call transfer, conference, and forward within that set of extensions.
- Circuit Switched Data
- A B-channel configuration that allows only data communication.
- Circuit Switched Voice
- A B-channel configuration that allows only voice communication.
- Circuit Switched Data and Voice (CSDV)
- Circuit switched voice and data. B-channel configuration that enables either circuit switched voice or data communication.
- Courier I
- Terminal adapter manufactured by US Robotics.
- Customer Access Line Charge (CALC)
- A Federal tariff charge, also referred to as an End User Common Line Charge (EUCL), or Subscriber Line Charge (SLC). Every ISDN line is charged one CALC or EUCL.
D
- Demarc/MPOE
- The "demarcation point", "Minimal Point Of Entry", or the point where the telephone company's wiring stops and your wiring begins. You can choose to do your wiring (also called Inside Wiring) yourself, or hire someone else, including the phone company, but the phone company will charge you extra for any wiring work performed on your side of the demarcation point.
- D-Channel
- One of the three standard channels on a BRI line. At 16 Kbps, a D-channel carries all signaling information and can carry low-speed packet data such as X.25 packet switching.
- DMS/DMS100
- The name of a central office switch manufactured by Northern Telecom . These switches use Custom (proprietary) or National ISDN-1 (NI-1) software. The DMS switches used by Southwestern Bell currently support the NI-1 standard.
F
- Firmware
- Software stored in EPROM (Erasable Programmable Read-Only Memory).
I
- Impact/Impact IQ
- Terminal Adapter manufactured by 3Com Corporation.
- Inside Wiring (Premises Wiring)
- Cabling infrastructure on any given site. Even though ISDN is designed to work over regular telephone wiring, very old cable will have to be upgraded. Typically, you have the option of doing it yourself, or you can have the phone company or a wiring vendor do it for a charge.
- ISDN
- Integrated Services Digital Network: A completely digital telecommunications network for carrying voice, data, images, and video at high speed by sending digitally-encoded signals. ISDN provides end-to-end digital service and can work on the copper wiring phone lines found in most homes and businesses today.
- ISDN Ordering Code
- A predefined number that tells the phone company how to provision your ISDN line, based on the requirements of your ISDN hardware.
L
- Line Extension (Repeater)
- A means for providing ISDN at distances beyond the normal limit (18,000 feet) between the Central Office and your location, or when the line signal loss exceeds 35.0 dB. Also known as a span repeater.
- Line or Loop Qualification
- A test that your phone company runs to make sure that your ISDN line complies with the distance and quality requirements of being 18,000 feet from the Central Office providing the ISDN service to you.
M
- MAX/MAX4000
- Hub manufactured by Ascend Communications Corp. Southwestern Bell Internet uses this equipment in all of their dial-up network nodes or Points of Presence (POPs).
- MP+
- Ascend Communications' proprietary software protocol which enables the user to combine two or more B-channels into a single, faster PPP connection.
- Multi-link PPP
- Allows you to combine two or more B-channels into a single, faster PPP connection. With Multi-link PPP, you can have a 128 Kbps PPP connection over a Basic Rate ISDN line.
N
- NI-1 (National ISDN-1) and NI-2 (National ISDN-2)
- A specification for a "standard" ISDN phone line. National ISDN 1 and National ISDN 2 are intended to be a set of standards to which every manufacturers' equipment should conform for maximum interoperability. NI3 is a future standard currently under development.
- NT-1 (Network Termination-1)
- The device that connects to your ISDN hardware and also works as a converter between an ISDN U-interface and an ISDN S/T-Interface. An NT-1 converts a line from a 2-wire to a 4-wire connection. Some ISDN adapters have a NT-1 already built into them. This is easier and less expensive than an external NT-1, but it may prevent you from connecting other equipment to your ISDN line.
P
- PBX
- Private Branch Exchange. A PBX is a private telephone switch that provides switching (including a full set of switching features) for an office or campus. PBXs often use proprietary digital-line protocols, although some are analog-based. Most modern digital PBXs could conceivably run a small town.
- Point-to-Point Protocol (PPP)
- A protocol that allows a computer to use TCP/IP to connect to other computers over a standard phone line using a high-speed modem.
- POTS
- Plain Old Telephone Service: conventional voice grade service and cabling infrastructure.
- Primary Rate Interface (PRI)
- A type of ISDN service that offers 23 B-channels at 64 Kbps and one D-channel at 64 Kbps (23B+D). In Europe, PRI provides for 30 B-channels and two D-channels (30B+1D).
R
- Repeater
- Device that acts as an amplifier. Also known as a Line Extender. This device is needed when the distance between the phone company's Central Office and your premises exceeds distance or dB loss limits.
- Router
- A Hardware device that connects two or more networks. A router determines where the destination computer is located, and then finds the best way to get there.
S
- Service Profile Identifier (SPID)
- A number or set of numbers assigned to your ISDN line by your phone company. In the U.S., one SPID is assigned to each channel. The switch uses SPIDs as unique identification numbers for each ISDN line, so it can determine where to send calls and signals.
- S/T-Interface
- The part of the ISDN line that connects to the computer or phone.
- Switch Type
- The type of equipment that the telephone company uses to provide you with ISDN service. Southwestern Bell uses both 5ESS and DMS100 switches in its central offices.
T
- Terminal Adapter (TA)
- A device that enables you to connect a non-ISDN terminal to an ISDN line.
- Terminal Equipment Identifier (TE1/TE2)
- Terminal Endpoint Identifier (TEI). The Terminal Endpoint Identifier is used to identify a specific piece of equipment on an ISDN connection. TE1 hardware is digital, whereas TE2 hardware is an analog piece of hardware requiring a TA. TEI1 equipment is ISDN ready; TEI2 is not.
- TID
- Additional equipment identifier for custom or NI-1 configuration on the DMS100 switch. Where Southwestern Bell uses NI-1 in its DMS100 switches, "00" is recommended as the TID. TIDS come in many different flavors and configurations.
- Twisted Pair
- In the telecommunications industry, wire is usually referred to in pairs rather than conductors. With the introduction of data transmissions, crosstalk (interference between individual conductors) became problematic. The fix is called Twisted Pair. This refers to individual pairs of wire that are twisted randomly. The twists create an inconsistent, ever changing EMF (ElectroMagnetic Field), thus preventing crosstalk. This novel concept eliminates the need for shielding and is also referred to as UTP, or Unshielded Twisted Pair.
U
- UART
- Universal Asynchronous Receiver Transmitter. A chip that acts as the intermediary between the computer and another device such as a terminal adapter. The 16550 is the current standard. 16450 and 8250 are older versions which do not support data transfer at ISDN speeds.
- U-Interface
- A 2-wire ISDN interface from an ISDN line to the central office; the most common ISDN interface.
V
- V.110/V.120
- V.120 is a North American standard for ISDN rate adapting used when two TAs "handshake" at any speed less than 64 Kbps. The European equivalent is called V.110. V.110 and V.120 are not compatible.
X
- X.25
- Packet switching protocol that lets computers communicate via wide area packet switched data networks.
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