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Glossary A-C D-G H-K L-Q R-Z
Data Service Unit (DSU)
See Channel Service Unit/Data Service Unit (CSU/DSU).
Data Terminal Equipment (DTE)
Equipment that comprises the endpoints in a connection over a data circuit. In a connection between a data terminal and host, the terminal, the host, and the associated modems or data modules comprise the DTE.
dB
Decibel.
D-channel
A data channel over which ISDN messages are transported to control the call setup of one or more Bchannels.
DCP
See Digital Communications Protocol (DCP).
DEFINITY
DEFINITY describes both Avaya’s flagship PBX product (hardware and software) and sometimes also the software application at the heart of the G350’s call control. That software application is now called Avaya Call Processing, though the use of the term DEFINITY is present in many historical documents. In the context of G350, it almost always describes the software application, including call control software as well as maintenance and administration functions that are included with it.
DEFINITY ONE
A version of DEFINITY running in a ProLogics cabinet with an NT processor complex (the RYON card). DEFINITY ONE runs Avaya Call Processing and Intuity messaging on this NT processor.
DEFINITY Wireless Business System (DWBS)
A wireless telecommunications system that integrates wireless capabilities into the DEFINITY Server.
DHCP
See Dynamic Host Configuration Protocol (DHCP).
Differentiated Services (DiffServ)
A protocol that is used to specify and control network traffic by class, so that certain types of traffic get precedence. For example, voice traffic, which requires a relatively uninterrupted flow of data, might get precedence over other kinds of network traffic. DiffServ is the most advanced method for managing traffic by Class of Service. DiffServ avoids simple priority tagging, and depends on more complex policy or rule statements to determine how to forward a given network packet.
DiffServ
See Differentiated Services (DiffServ).
Digital Communications Protocol (DCP)
A proprietary protocol that is used to transmit digitized voice and data over the same communications link. A DCP link consists of two 64-kbps Information (I) channels, and one 8-kbps Signaling (S) channel. The DCP protocol supports two information-bearing channels, and thus two telephones or data modules. The I1 channel is the DCP channel that is assigned on the first page of the 8411 station form. The I2 channel is the DCP channel that is assigned on the analog adjunct page of the 8411 station form, or on the data module page.
Digital Signal-0 (DS0)
See Digital Signal Level n (DS-n).
Digital Signal-1 (DS1)
See Digital Signal Level n (DS-n).
Digital Signal Level n (DS-n)
A term for the series of standard digital transmission rates or levels that are used to classify the capacities of digital lines and trunks. Signals are based on DS0, and range upward to DS4. DS0 is a transmission rate of 64 Kbps, which is the bandwidth that is normally used for one telephone channel. DS0 is a single 64-kbps channel in a T1 facility or an E1 facility, and consists of 8 bits in a T1 frame or an E1 frame every 125 microseconds. DS1, used as the signal in the T-1 carrier, is 24 DS0 (64 Kbps) signals that are transmitted using pulse-code modulation (PCM) and time-division multiplexing (TDM). DS-2 is four DS1 signals that are multiplexed together to produce a rate of 6.312 Mbps. DS-3, the signal in the T-3 carrier, carries a multiple of 28 DS1 signals or 672 DS0s or 44.736 Mbps. Digital Signal n is based on the ANSI T1.107 guidelines.
Digital Signal Processor (DSP)
A specialized microprocessor that processes a stream of bits in real time. In the telecommunications industry, DSPs are used for such things as echo cancellation, call progress monitoring, voice processing, and the compression of voice and video signals. See also codec.
Digital-to-Analog Converter (DAC)
A device that converts data in digital form to the corresponding analog signals.
Distributed IP Telephony
The architecture for leveraging IP networks to carry voice between phones, softphones, wireless devices, servers, and gateways. This integrates communications across distributed organizations, increasing functionality and lowering costs. (Also sometimes called client-server, converged or LAN telephony.)
DLCI
See Data Link Connection Identifier (DLCI).
Domain Name System (DNS)
A hierarchical network-naming scheme. DNS servers provide a mapping of domain names to IP addresses.
Dot1Q
Standard for VLAN tagging under the IEEE 802.1Q VLAN standard.
DRAM
See Dynamic Random Access Memory (DRAM).
DS0
See Digital Signal Level n (DS-n).
DS1
See Digital Signal Level n (DS-n).
DS3
See Digital Signal Level n (DS-n).
DSI
Digital Signal Interface.
DSP
See Digital Signal Processor (DSP).
DSU
See Channel Service Unit/Data Service Unit (CSU/DSU).
DTMF
See Dual-Tone Multifrequency (DTMF).
Dual-Tone Multifrequency (DTMF)
Touchtones that are used for in-band telephone signaling.
duplex mode
The state of the device with regard to simultaneous transmission and reception of information. In full duplex mode, also known as bisynchronous communication, the device or circuit permits simultaneous transmission and reception. In half duplex mode, also known as asynchronous communication, the device or circuit does not permit simultaneous transmission and reception.
Dynamic Host Configuration Protocol (DHCP)
An IETF protocol (RFCs 951, 1534, 1542, 2131, and 2132) that dynamically assigns IP addresses from a pool of addresses.
Dynamic Random Access Memory (DRAM)
Read/write memory that must be continually refreshed to maintain the stored data. See also Random Access Memory (RAM).
E&M
See Ear and Mouth (E&M) signaling.
E1
E1 is a European digital transmission format that was devised by the ITU-TS and named by the Conference of European Postal and Telecommunication Administration (CEPT). E1 is the equivalent of the North American T-carrier system format. E2 through E5 are carriers in increasing multiples of the E1 format. The E1 signal format carries data at a rate of 2.048 million bits per second, and can carry 32 channels of 64 Kbps each. E1 carries at a somewhat higher data rate than T1, which carries 1.544 million bits per second. The reason for this higher rate is that E1, unlike T1, does not do bitrobbing, and all 8 bits per channel are used to code the signal. E1 and T1 can be interconnected for international use. The E2 signal format carries four multiplexed E1 signals with a data rate of 8.448 million bits per second. The E3 signal format 16 E1 signals with a data rate of 34.368 million bits per second.
Ear and Mouth (E&M) signaling
Trunk supervisory signaling that is used between two communications systems. E&M signaling information is transferred through 2-state voltage conditions (on the E and M leads) for analog applications, and through a single bit for digital applications.
ECC
Error Correct Code.
EIA
See Electronics Industries Association (EIA).
EIA-232
A physical interface specified by the Electronic Industries Association (EIA). EIA-232 transmits and receives asynchronous data at speeds of up to 19.2 kilobits per second over cable distances of up to 50 feet. EIA-232 replaces RS-232 protocol in some Avaya MultiVantage applications.
Electromagnetic Interference (EMI)
Interference in signal transmission that is caused by the radiation of electrical and magnetic fields.
Electronics Industries Association (EIA)
A trade association of the electronics industry that establishes electrical and functional standards for the member companies.
E-mail automation
Providing an automated scripted response based on key words found in a customer-generated e-mail message, or integrating e-mail requests into call distribution, queuing, and routing processes.
EMC
Electromagnetic Compatibility. A term that typically encompasses radio-frequency and conducted radiation, immunity/susceptibility, power surges and transients, and Electrostatic Discharge (ESD).
Emergency Transfer Relay (ETR)
A feature that provides basic telephone services in the event of a power outage or a failed connection to Avaya Communications Manager. Using ETR, an analog relay can be set up to connect an outside telephone exchange to an analog telephone.
EMI
See Electromagnetic Interference (EMI).
Erlang
A unit of traffic intensity, or load, that is used to express the amount of traffic that is needed to keep one facility busy for one hour. One Erlang equals 36 hundred Call Seconds (CCS).
Ethernet
One of the most widely implemented LAN standards, Ethernet is standardized as IEEE 802.3. Ethernet uses the CSMA/CD access method to handle simultaneous demands, and supports data transfer rates of 10 Mbps. A newer version of Ethernet, called 100Base-T (or Fast Ethernet), supports data transfer rates of 100 Mbps. The newest version, Gigabit Ethernet, supports data rates of 1 gigabit per second.
Ethernet L2 switch
In the Avaya G700 Media Gateway and in the Avaya stackable switch and router family, an Ethernet L2 switch consists of one or more 8-port, wire-speed Application-Specific Integrated Circuit (ASIC) devices.
Ethernet switch
A device that provides for port multiplication by having more than one network segment. An Ethernet switch directs data only to the target device, instead of to all devices that are attached to the Local Area Network (LAN).
ETR
See Emergency Transfer Relay (ETR).
ETSI
See European Telecommunications Standards Institute (ETSI).
EU
European Union. A group of European nations that, among other things, have agreed on common type approval requirements.
European Telecommunications Standards Institute (ETSI)
An organization that works to promote integrated telecommunications in the European community. ETSI can be viewed as the counterpart of the American National Standards Institute (ANSI).
external call
A connection between a user of a communications system and a party who is either on the public network or on another communications system in a private network.
external communications controller
An external processor running the Avaya Call Processing application, i.e. StingRay or G3i/r or IP 600, controlling G350 Media Gateways. See also Internal Communications Controller (ICC).
External Media Server (EMS)
An external server that is running Avaya Communication Manager. An Avaya S8700 Media Server that is controlling Avaya G700 Media Gateways is an example of an external server.
FAC
Feature Access Code.
FCC
Federal Communications Commission.
FCS
Frame Check Sequence. A field added to a frame for error-control purposes.
FDX
See Full Duplex (FDX).
File Transfer Protocol (FTP)
An Internet protocol standard that is used to copy files from one computer to another. See also Trivial File Transfer Protocol (TFTP).
flash memory
Non-volatile memory that can be erased and reprogrammed by the microprocessor to which it is connected.
fractional T1
A fractional T-1 is a T-1 digital phone line in the North American T-carrier system that is leased to a customer at a fraction of its data-carrying capacity and at a correspondingly lower cost. A T-1 line contains 24 channels, each with a data transfer capacity of 64 Kbps. The customer can rent some number of the 24 channels. The transmission method and speed of transfer remain the same. Overhead bits and framing are still used, but the unrented channels simply contain no data.
fragment
Ethernet packet shorter than 576 bits (usually the result of a collision).
frame
A logical grouping of information sent as a Data Link Layer unit over a transmission medium. The word frame often refers to the header and trailer, used for synchronization and error control, that surrounds the user data contained in the unit.
Frame Relay (FR)
Frame Relay is a telecommunication service designed for cost-efficient data transmission for intermittent traffic between Local Area Networks (LANs) and end-points in a Wide Area Network (WAN). Frame Relay puts data in a variable-size unit called a frame and leaves any necessary error correction (retransmission of data) up to the end-points, which speeds up overall data transmission. For most services, the network provides a Permanent Virtual Circuit (PVC). This means that the customer sees a continuous, dedicated connection without having to pay for a full-time leased line, while the service provider figures out the route each frame travels to its destination and can charge based on usage. An enterprise can select a particular level of service quality to prioritize some frames and making others less important. Frame Relay is offered by a number of service providers, including AT&T. Frame Relay is provided on fractional T-1 or full T-carrier system carriers. Frame Relay complements and provides a mid-range service between Integrated Services Digital Network, which offers bandwidth at 128 Kbps, and Asynchronous Transfer Mode (ATM), which operates in somewhat similar fashion to Frame Relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame Relay is based on the older X.25 packet switching technology, which was designed for transmitting analog data such as voice conversations. Unlike X.25, which was designed for analog signals, Frame Relay is a fast packet technology, which means that the protocol does not attempt to correct errors. When an error is detected in a frame, it is simply “dropped” (thrown away). The end points are responsible for detecting and retransmitting dropped frames. (However, the incidence of error in digital networks is extraordinarily small relative to analog networks.) Frame Relay is often used to connect local area networks with major backbones, as well as on public wide area networks and also in private network environments with leased lines over T-1 lines. Since it requires a dedicated connection during the transmission period, it is not ideally suited for voice or video transmission, which require a steady flow of transmissions. However, under certain circumstances, it can be used for voice and video transmission. Frame Relay relays packets at the Data Link Layer of the Open Systems Interconnection (OSI) model rather than at the network layer. A frame can incorporate packets from different protocols, such as Ethernet and X.25. It is variable in size and can be as large as a thousand bytes or more.
FTP
See File Transfer Protocol (FTP).
Full Duplex (FDX)
A circuit or device permitting simultaneous data transmission between sending and receiving stations. See also duplex mode.
G.711
A mu-law or an a-law, 64-Kbps codec.
G.723
A 5.3 or 6.3-Kbps audio codec.
G.729
An 8-Kbps audio-codec.
GA
General Availability.
gatekeeper
A term that is defined by the H.323 standard to describe the entity that performs most of the authorization, routing, and feature functionality in an H.323 system.
Gateway (GW)
In networking, a combination of hardware and software that links two different types of networks. In G350, the G350 Media Gateway (CMG) is an entity on the network that links the circuit switched network (analog, DCP phones, and E1/T1 trunks) to the packet based network (LAN). The CMG provides service circuits (tones and audio mixers) and conversion resources for traversing legacy telephony and IP network domains with voice-oriented bearer and signaling information.
GUI
Graphical User Interface.
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