| AutoTrack |
This
COMPLIS function makes it possible to automatically
track a session no matter what B channel is allocated
for communications
|
|
| Auxiliary
Power Supply (APS) |
Supplementary power feeding which supplies the Power Source 1 when the NT is not supplying power. This accessory is used in the English public networks, for example.
|
|
Basic
Rate Access (BRA)
Basic Rate Interface (BRI) |
The ISDN standard governing how a customer's desktop terminals and telephones can be connected to an ISDN switch.
The BRA is an ISDN standardised access offering two B Channels (64 kbits) for voice or data transmission and one D Channel for Signaling (16 kbits/s) according to the ITU-T Standard Rec. I.430.
|
|
| B
channel |
The circuit-switched 'bearer' channel that is a fundamental component of ISDN interfaces. It carries either voice or data at 64,000 bits (64 kilobits) per second in either direction.
|
|
| Bearer
service |
The basic set of services offered over the B channel that provides the capability to exchange signals between two user-network interfaces.
|
|
| Bit
Error Rate Test (BER test) |
Measurement of the transmission quality by the analysis of the bit error rate.
|
|
| Channel |
Physical path for analog or digital transmission of voice, data, facsimile or television images between two telephones or other terminals.
|
|
| CHAP |
Challenge
Handshake Authentication Protocol used with PPP.
Defined by RFC 1994.
|
|
| Circuit |
A
physical transmission link between two telephones
or terminals capable of carrying voice, data and
image signals.
|
|
| CI
channel |
This channel is conveyed by the digital transmission system in both directions between the LT and NT1 and is relating to the U interface (BRA).
It is used to transfer information concerning operation maintenance and activation/deactivation of the digital transmission system and of the access digital section.
The Cl channel contents are also called Cl bits or overhead bits.
|
|
| Common
Channel Signalling (CCS) = CCITT # 7 |
Signalling
protocol used on international links in order to
interconnect telephone exchanges.
|
|
| Consultative
Committee for International Telephone and Telegraph (CCITT) |
A committee of the International Telecommunication Union (ITU), creating recommendations regarding public telegraph, telephone, and data networks; originally organized in 1865, the CCITT is the oldest intergovernmental agency. Renamed ITSS in March 1993.
|
|
| Customer
Premises Equipment (CPE) |
American term for a terminal equipment called TE in the ISDN standards, i.e. any communications equipment placed at the customer's site, including modems, telephone sets, PBXs and NT1s.
|
|
| D
channel |
The 'data' channel of the ISDN interface, used to carry packet-switched control signals and data relating to customer call.
In the BRI, the D channel operates at 16 Kbits/s. In the PRI, the D channel operates at 64 Kbits/s.
|
|
| Digital
Subscriber Signalling (DSS) |
Signalling
protocol between the terminal and the network. There
are various national (VN4, 1TR6, etc.) or international
(EDSS-1, Q.931, etc.) versions.
|
|
| Digital
Subscriber Signalling System No 1 (DSS 1) |
The ISDN user-network interface, comprising a data link layer and network layer; described in ITU (ex-CCITT) Recommendations Q.920-series (LAPD/LAPF) and Q.930-series recommendations, respectively.
|
|
| Digital
transmission |
A method of sending and receiving information coded with on-and-off pulses of electricity or light.
|
|
| Emulation |
Capability to automatically replace all or part of a network or terminal equipment (TE).
|
|
| Encapsulation |
Use of an intermediary protocol to ensure the transport of a non-compatible protocol with the network. Generally, X.25 or PPP is used.
|
|
| EOC
(Embedded Operation Channel) bits |
The Embedded Operation Channel is a sub-channel of the Cl channel. It conveys the EOC protocol operating in a repetitive command/response mode. The EOC protocol is typically used to ask the NT1 to loop back data channels (B1, B2, 2B+D) for maintenance purposes.
|
|
| European
Telecommunications Standards Institute (ETSI) |
An organization, headquartered in France, responsible for creating common telecommunications standards for the European market.
|
|
| Gateway
/ router |
Device used to interconnect two networks having a different topology
|
|
| G.821 |
ITU (ex-CCITT) Recommendation defining the performance and quality of a transmission system.
|
|
| I.430 |
The ITU (ex-CCITT) Recommendation describing the physical layer aspects of the basic rate interface (BRI).
|
|
| I.431 |
The
ITU (ex-CCITT) Recommendation describing the physical
layer aspects of the primary rate interface (PRI).
|
|
| IETF |
Internet
Engineering Task Force.
|
|
| IP |
Internet
Protocol for Unix, LAN or Internet environments.
|
|
| International
Telecommunication Union (ITU) |
An
agency of the United Nations, the parent organization
of the CCITT (now called the ITSS).
|
|
| ISDN |
Integrated Services Digital Network. As officially defined by ITU (ex-CCITT):
A digital network that provides a wide variety of communications services, a standard set of user-network messages, and integrated access to the network with worldstandwide ardised interfaces.
|
|
| International
Organization for Standardization (ISO) |
An international standards organization that comprises national standards bodies; ANSI, for example, is the U.S. representative to ISO. ISO's data communications standards include HDLC, the OSI Reference Model, and OSI protocols.
|
|
ITU
Telecommunications Standardization Sector (ITSS) |
The new name of the CCITT after the ITU's reorganization in March 1993. See CCITT.
|
|
| Kbps
(kilobits per second) |
Thousands of bits per second, a standard unit of transmission speed.
|
|
| Layer |
Layers are commonplace in the hierarchy of telecommunications functions. There are 7 layers defined in the OSI model. For example, layer 3 processes network functions (addressing).
|
|
| Line
Termination (LT) |
Board in the switch on which the subscriber line is being connected.
|
|
| Local
Area Network (LAN) |
A communications network that interconnects devices over a geographically small area (e.g. within a building).
|
|
| Metropolitan
Area Network (MAN) |
A network service that provides high speed and low delay over a metropolitan area and initial B-ISDN-like services; the Switched Multimegabit Data Service is one such MAN offering that uses cell relay transport. This category includes the networks up to 100 km. (e.g. FDDI.)
|
|
| Mbps
(megabits per second) |
One million bits per second, a measurement of transmission speed.
|
|
| Memorandum
of Understanding (MoU) |
Treaty signed in 1989 by 19 European countries and intended to commit on the ISDN development and interoperability.
|
|
| MLP
or MP |
Protocol used over PPP to connect two remote routers using several parallel transmission paths (e.g. 2 ISDN B channels). Defined by RFC 1990, update of RFC 1717.
|
|
| Monitoring |
Ability to capture the information exchanged on a line in high-impedance without disturbing communications.
|
|
| Network |
A collection of communicating devices, switches, and links that are interconnected and autonomous.
|
|
| Network
Termination (NT) |
Kind of box at the end of the line coming from the switch, which converts the UO code in a S/T bus.
|
|
| Network
Termination type 1 (NT1) |
The ISDN device responsible for the termination of the ISDN transmission facility at the customer premises.
|
|
| Network
Termination type 2 (NT2) |
An ISDN device responsible for on-premises communication distribution, such as a PBX, LAN-router, or host computer.
|
|
| NT
simulation |
The NT simulation is the possibility to simulate the network in order to test the PBXs and terminal equipment.
|
|
| Open
System Interconnection (OSI) Reference Model |
A seven-layer model architecture for open systems, allowing communication between computers from different vendors using different network architectures; initially proposed by ISO, it has been adopted by ITU (ex-CCITT) and all major computer manufacturers around the world; the model and protocols are defined in CCITT X.200-series recommendations.
|
|
| PAP |
Password Authentication Protocol in PPP.
|
|
| PBX |
Private Branch Exchange: a private telephone switch. It is connected to groups of lines from one or more central offices, and to all of the telephones - and often, much of the data processing, facsimile and video equipment - at the location served.
|
|
| Packet |
A unit of digital data with a set number of bits, including some bits that serve as an address code. The packet can be sent through a packet switching network by the best route, and reunited at its destination with the other message packets, regardless of the route each took, or the order of their arrival.
|
|
| Packet
switching |
A technique for transmitting data in which the data is subdivided into packets by a PAD. Each packet carries the address of its destination and its sequencing information. Packets from many users are interleaved on a single communications channel. Defined by ITU (ex-CCITT) X.25.
|
|
| Phantom
power |
In the CCITT BRI standard, the ability of the NT1 to provide power to the TE1/TA over the transmit and receive power pair.
|
|
| Physical
layer |
Layer 1 of the OSI Reference Model; primarily responsible for the transport of bits between adjacent devices in a network, describing electrical and mechanical characteristics of the connection and media.
|
|
| PPP |
Datacom method used to transport multi-protocol LAN traffic between routers over leased line or ISDN. PPP is also used for Internet access via ISDN. Defined by RFC 1661 and RFC 1618.
|
|
| Primary
Rate Access (PRA) Primary Rate Interface (PRI) |
In the United States, the PRI consists of 23 B or 'bearer' channels operating at 64 Kbps, and one D or 'data' channel also functioning at 64 Kbps. The combined signal-carrying capacity is 1.544 Mbps (T1) -equivalent to a digital signal hierarchy level of DS-1. In Europe, the PRI consists of 30 B channels and one D channel combined in 2.048 Mbps.
|
|
| Private
Automatic Branch Exchange (PABX) |
|
| Private
Branch Exchange (PBX) |
A customer-site telephone switch; common usage of this term today implies that a PBX is an automatic switch, although a PBX could be under the control of an operator (or attendant).
|
|
| Private
network |
A leased, private transmission network that links multiple locations of a company or other organization, using voice and/or data communications lines reserved exclusively for that company's traffic.
|
|
| Protocol |
In communications, the set of rules that governs the exchange of information between two devices, allowing them to effectively communicate with each other. These rules define procedures for the transfer of information in a computing or communications system. Data communications protocols deal with, among other things, call set-up procedures and formatting.
|
|
| Public
switched network |
The combined transmission facilities of the world's telephone companies and administrations, including all those circuits available to subscribers on an unrestricted basis.
|
|
| Pulse
code modulation (PCM) |
Voice digitization scheme that samples an analog voice signal 8000 times per second and converts each sample to an 8-bit code, yielding a digital voice rate of 64 kbps, allowing 30 timeslots on a 2-Mbps line; defined in ITU (ex-CCITT) Recommendation G.711.
|
|
| Regenerator |
Device which recognizes signals which it is supposed to echo in the same position with their original amplitude.
|
|
| RFC |
Request For Comment, draft or approved documents managed by the IETF to define dataxom industry standards.
|
|
| Router |
|
| Simulation |
Capability to replace semiautomatically all or part of a network or terminal equipment (TE), in order to generate correct or incorrect operating cases.
|
|
| Subaddress |
Additional addressing that may be used in an ISDN call to identify a specific terminal at an ISDN interface, such as a specific phone on a PBX. Subaddresses do not identify the ISDN interface in any way, thus are not used by the network for routing purposes.
|
|
| Supplementary
services |
Additional services offered to an ISDN customer, allowing the network to provide the user with more dynamic and flexible control of how they use the network. Defined in the I.250-series recommendations, categories of supplementary services are number identification, call offering, call completion, multiparty, community of interest, charging, and additional information transfer. The supplementary services are offered by the network. They are dealing with call identification, call forwarding, portability, filtering, display of tax advice, etc.
|
|
| Switch |
Telecommunications equipment which controls the routing of transmission signals entering and leaving a central office or a toll office. On customer premises, a PBX functions as a private switch that links various phone extensions to each other and to the outside world.
|
|
| Switching |
The process of interconnecting two devices on a network using shared resources. Two common approaches are circuit switching and packet switching.
|
|
| Telecommunications |
The transmission of signals representing voice, video, data or images over a distance.
|
|
| Telecommunications
service |
|
| Teleservice |
An ISDN value-added service that may be offered to a subscriber by another ISDN user or by the network itself.
|
|
| Terminal
adapter (TA) |
A protocol converter used to allow a non-ISDN terminal (TE2) to access the network using ISDN protocols and procedures.
|
|
| Terminal
End-point Identifier (TEI) |
A subfield in the LAPD Address field that identifies a given TE device on the ISDN interface.
|
|
| Terminal
equipment (TE) |
Any ISDN-compatible device that may be placed on the network, such as a telephone, fax, PBX, TV, PC or computer.
|
|
| Terminal
equipment type 1 (TE1) |
ISDN-compatible terminal equipment.
|
|
| Terminal
equipment type 2 (TE2) |
Non-ISDN-compatible equipment.
|
|
| TE
simulation |
The TE simulation is the possibility to simulate a terminal in order to test the network.
|
|
| U
interface |
Interface between the network termination NT (on the customer's site) and the line termination LT (at the public exchange).
The main line codes used at the ISDN BRA U interfaces are : 2B1Q and 4B3T.
|
|
| Videotex |
An information storage and retrieval service using text and graphical information.
|
|
| Virtual
circuit (VC) |
A seemingly real connection between two points in a packet switching or Frame Relay networks. It appears to the user to be a dedicated, or private circuit. Several virtual circuits can coexist on a single physical transmission facility.
|
|
| Wide
Area Network (WAN) |
Long-distance public or private network, such as a national or international telephone or data network. It may be switched or multiplexer-based.
|
|
| X.25 |
The primary ITU (ex-CCITT) protocol governing packet switching. A ITU (ex-CCITT) recommendation describing layers 1 through 3 of the user-network interface for packet switched public data networks.
|
|
Two
B channels for user voice or data information (64 Kbps) in circuit
mode providing end-to-end digital transmission service.
